diff --git a/extensions/vscode-api-tests/src/singlefolder-tests/notebook.document.test.ts b/extensions/vscode-api-tests/src/singlefolder-tests/notebook.document.test.ts
index bb8b9a01674..70e6e704231 100644
--- a/extensions/vscode-api-tests/src/singlefolder-tests/notebook.document.test.ts
+++ b/extensions/vscode-api-tests/src/singlefolder-tests/notebook.document.test.ts
@@ -248,67 +248,6 @@ suite('Notebook Document', function () {
 		assert.strictEqual(data.changes[0].items[1], document.cellAt(1));
 	});
 
-	test('workspace edit API (appendNotebookCellOutput, replaceCellOutput, event)', async function () {
-		const uri = await utils.createRandomFile(undefined, undefined, '.nbdtest');
-		const document = await vscode.notebook.openNotebookDocument(uri);
-
-		const outputChangeEvent = utils.asPromise<vscode.NotebookCellOutputsChangeEvent>(vscode.notebook.onDidChangeCellOutputs);
-		const edit = new vscode.WorkspaceEdit();
-		const firstCellOutput = new vscode.NotebookCellOutput([new vscode.NotebookCellOutputItem('foo', 'bar')]);
-		edit.appendNotebookCellOutput(document.uri, 0, [firstCellOutput]);
-		const success = await vscode.workspace.applyEdit(edit);
-		const data = await outputChangeEvent;
-
-		assert.strictEqual(success, true);
-		assert.strictEqual(document.cellCount, 1);
-		assert.strictEqual(document.cellAt(0).outputs.length, 1);
-		assert.deepStrictEqual(document.cellAt(0).outputs, [firstCellOutput]);
-
-		assert.strictEqual(data.document === document, true);
-		assert.strictEqual(data.cells.length, 1);
-		assert.strictEqual(data.cells[0].outputs.length, 1);
-		assert.deepStrictEqual(data.cells[0].outputs, [firstCellOutput]);
-
-
-		{
-			const outputChangeEvent = utils.asPromise<vscode.NotebookCellOutputsChangeEvent>(vscode.notebook.onDidChangeCellOutputs);
-			const edit = new vscode.WorkspaceEdit();
-			const secondCellOutput = new vscode.NotebookCellOutput([new vscode.NotebookCellOutputItem('foo', 'baz')]);
-			edit.appendNotebookCellOutput(document.uri, 0, [secondCellOutput]);
-			const success = await vscode.workspace.applyEdit(edit);
-			const data = await outputChangeEvent;
-
-			assert.strictEqual(success, true);
-			assert.strictEqual(document.cellCount, 1);
-			assert.strictEqual(document.cellAt(0).outputs.length, 2);
-			assert.deepStrictEqual(document.cellAt(0).outputs, [firstCellOutput, secondCellOutput]);
-
-			assert.strictEqual(data.document === document, true);
-			assert.strictEqual(data.cells.length, 1);
-			assert.strictEqual(data.cells[0].outputs.length, 2);
-			assert.deepStrictEqual(data.cells[0].outputs, [firstCellOutput, secondCellOutput]);
-		}
-
-		{
-			const outputChangeEvent = utils.asPromise<vscode.NotebookCellOutputsChangeEvent>(vscode.notebook.onDidChangeCellOutputs);
-			const edit = new vscode.WorkspaceEdit();
-			const thirdOutput = new vscode.NotebookCellOutput([new vscode.NotebookCellOutputItem('foo', 'baz1')]);
-			edit.replaceNotebookCellOutput(document.uri, 0, [thirdOutput]);
-			const success = await vscode.workspace.applyEdit(edit);
-			const data = await outputChangeEvent;
-
-			assert.strictEqual(success, true);
-			assert.strictEqual(document.cellCount, 1);
-			assert.strictEqual(document.cellAt(0).outputs.length, 1);
-			assert.deepStrictEqual(document.cellAt(0).outputs, [thirdOutput]);
-
-			assert.strictEqual(data.document === document, true);
-			assert.strictEqual(data.cells.length, 1);
-			assert.strictEqual(data.cells[0].outputs.length, 1);
-			assert.deepStrictEqual(data.cells[0].outputs, [thirdOutput]);
-		}
-	});
-
 	test('document save API', async function () {
 		const uri = await utils.createRandomFile(undefined, undefined, '.nbdtest');
 		const notebook = await vscode.notebook.openNotebookDocument(uri);
@@ -375,45 +314,6 @@ suite('Notebook Document', function () {
 		assert.strictEqual(cellDoc.languageId, 'css');
 	});
 
-	test('#117273, Add multiple outputs', async function () {
-
-		const resource = await utils.createRandomFile(undefined, undefined, '.nbdtest');
-		const document = await vscode.notebook.openNotebookDocument(resource);
-
-		const edit = new vscode.WorkspaceEdit();
-		edit.replaceNotebookCellOutput(document.uri, 0, [
-			new vscode.NotebookCellOutput(
-				[new vscode.NotebookCellOutputItem('application/x.notebook.stream', '1', { outputType: 'stream', streamName: 'stdout' })],
-				{ outputType: 'stream', streamName: 'stdout' }
-			)
-		]);
-		let success = await vscode.workspace.applyEdit(edit);
-
-		assert.ok(success);
-		assert.strictEqual(document.cellAt(0).outputs.length, 1);
-		assert.strictEqual(document.cellAt(0).outputs[0].outputs.length, 1);
-		assert.deepStrictEqual(document.cellAt(0).outputs[0].metadata, { outputType: 'stream', streamName: 'stdout' });
-		assert.deepStrictEqual(document.cellAt(0).outputs[0].outputs[0].metadata, { outputType: 'stream', streamName: 'stdout' });
-
-		const edit2 = new vscode.WorkspaceEdit();
-		edit2.appendNotebookCellOutput(document.uri, 0, [
-			new vscode.NotebookCellOutput(
-				[new vscode.NotebookCellOutputItem('hello', '1', { outputType: 'stream', streamName: 'stderr' })],
-				{ outputType: 'stream', streamName: 'stderr' }
-			)
-		]);
-		success = await vscode.workspace.applyEdit(edit2);
-		assert.ok(success);
-
-		assert.strictEqual(document.cellAt(0).outputs.length, 2);
-		assert.strictEqual(document.cellAt(0).outputs[0].outputs.length, 1);
-		assert.strictEqual(document.cellAt(0).outputs[1].outputs.length, 1);
-		assert.deepStrictEqual(document.cellAt(0).outputs[0].metadata, { outputType: 'stream', streamName: 'stdout' });
-		assert.deepStrictEqual(document.cellAt(0).outputs[0].outputs[0].metadata, { outputType: 'stream', streamName: 'stdout' });
-		assert.deepStrictEqual(document.cellAt(0).outputs[1].metadata, { outputType: 'stream', streamName: 'stderr' });
-		assert.deepStrictEqual(document.cellAt(0).outputs[1].outputs[0].metadata, { outputType: 'stream', streamName: 'stderr' });
-	});
-
 	test('dirty state - complex', async function () {
 		const resource = await utils.createRandomFile(undefined, undefined, '.nbdtest');
 		const document = await vscode.notebook.openNotebookDocument(resource);
diff --git a/extensions/vscode-api-tests/src/singlefolder-tests/notebook.test.ts b/extensions/vscode-api-tests/src/singlefolder-tests/notebook.test.ts
index d593df11168..71cf55acee5 100644
--- a/extensions/vscode-api-tests/src/singlefolder-tests/notebook.test.ts
+++ b/extensions/vscode-api-tests/src/singlefolder-tests/notebook.test.ts
@@ -1169,33 +1169,6 @@ suite('Notebook API tests', function () {
 		await closeAllEditors();
 	});
 
-	test('#116598, output items change event.', async function () {
-
-		const resource = await createRandomNotebookFile();
-		await vscode.commands.executeCommand('vscode.openWith', resource, 'notebookCoreTest');
-
-		const edit = new vscode.WorkspaceEdit();
-		edit.appendNotebookCellOutput(resource, 0, [new vscode.NotebookCellOutput([
-			new vscode.NotebookCellOutputItem('application/foo', 'bar'),
-			new vscode.NotebookCellOutputItem('application/json', { data: true }, { metadata: true }),
-		])]);
-		await vscode.workspace.applyEdit(edit);
-		assert.strictEqual(vscode.window.activeNotebookEditor!.document.cellAt(0).outputs.length, 1);
-		assert.strictEqual(vscode.window.activeNotebookEditor!.document.cellAt(0).outputs[0].outputs.length, 2);
-
-		const appendEdit = new vscode.WorkspaceEdit();
-		const newItem = new vscode.NotebookCellOutputItem('text/plain', '1');
-		appendEdit.appendNotebookCellOutputItems(
-			resource,
-			0,
-			vscode.window.activeNotebookEditor!.document.cellAt(0).outputs[0].id,
-			[newItem]
-		);
-		await vscode.workspace.applyEdit(appendEdit);
-		assert.strictEqual(vscode.window.activeNotebookEditor!.document.cellAt(0).outputs[0].outputs.length, 3);
-		assert.deepStrictEqual(vscode.window.activeNotebookEditor!.document.cellAt(0).outputs[0].outputs[2], newItem);
-	});
-
 	test('#115855 onDidSaveNotebookDocument', async function () {
 		const resource = await createRandomNotebookFile();
 		const notebook = await vscode.notebook.openNotebookDocument(resource);
diff --git a/src/vs/vscode.proposed.d.ts b/src/vs/vscode.proposed.d.ts
index a3b436bc885..900695a4f13 100644
--- a/src/vs/vscode.proposed.d.ts
+++ b/src/vs/vscode.proposed.d.ts
@@ -1410,18 +1410,11 @@ declare module 'vscode' {
 		replaceNotebookMetadata(uri: Uri, value: NotebookDocumentMetadata): void;
 		replaceNotebookCells(uri: Uri, range: NotebookRange, cells: NotebookCellData[], metadata?: WorkspaceEditEntryMetadata): void;
 		replaceNotebookCellMetadata(uri: Uri, index: number, cellMetadata: NotebookCellMetadata, metadata?: WorkspaceEditEntryMetadata): void;
-
-		//todo@API remove output modifications?
-		replaceNotebookCellOutput(uri: Uri, index: number, outputs: NotebookCellOutput[], metadata?: WorkspaceEditEntryMetadata): void;
-		appendNotebookCellOutput(uri: Uri, index: number, outputs: NotebookCellOutput[], metadata?: WorkspaceEditEntryMetadata): void;
-		replaceNotebookCellOutputItems(uri: Uri, index: number, outputId: string, items: NotebookCellOutputItem[], metadata?: WorkspaceEditEntryMetadata): void;
-		appendNotebookCellOutputItems(uri: Uri, index: number, outputId: string, items: NotebookCellOutputItem[], metadata?: WorkspaceEditEntryMetadata): void;
 	}
 
 	export interface NotebookEditorEdit {
 		replaceMetadata(value: NotebookDocumentMetadata): void;
 		replaceCells(start: number, end: number, cells: NotebookCellData[]): void;
-		replaceCellOutput(index: number, outputs: NotebookCellOutput[]): void;
 		replaceCellMetadata(index: number, metadata: NotebookCellMetadata): void;
 	}
 
diff --git a/src/vs/workbench/api/common/extHostNotebookEditor.ts b/src/vs/workbench/api/common/extHostNotebookEditor.ts
index 24b8b687742..2c1dcaa34b0 100644
--- a/src/vs/workbench/api/common/extHostNotebookEditor.ts
+++ b/src/vs/workbench/api/common/extHostNotebookEditor.ts
@@ -57,17 +57,6 @@ class NotebookEditorCellEditBuilder implements vscode.NotebookEditorEdit {
 		});
 	}
 
-	replaceCellOutput(index: number, outputs: vscode.NotebookCellOutput[]): void {
-		this._throwIfFinalized();
-		this._collectedEdits.push({
-			editType: CellEditType.Output,
-			index,
-			outputs: outputs.map(output => {
-				return extHostConverter.NotebookCellOutput.from(output);
-			})
-		});
-	}
-
 	replaceCells(from: number, to: number, cells: vscode.NotebookCellData[]): void {
 		this._throwIfFinalized();
 		if (from === to && cells.length === 0) {
diff --git a/src/vs/workbench/api/common/extHostTypes.ts b/src/vs/workbench/api/common/extHostTypes.ts
index 42a6d5c55df..828cc92474f 100644
--- a/src/vs/workbench/api/common/extHostTypes.ts
+++ b/src/vs/workbench/api/common/extHostTypes.ts
@@ -706,30 +706,6 @@ export class WorkspaceEdit implements vscode.WorkspaceEdit {
 		}
 	}
 
-	replaceNotebookCellOutput(uri: URI, index: number, outputs: vscode.NotebookCellOutput[], metadata?: vscode.WorkspaceEditEntryMetadata): void {
-		this._editNotebookCellOutput(uri, index, false, outputs, metadata);
-	}
-
-	appendNotebookCellOutput(uri: URI, index: number, outputs: vscode.NotebookCellOutput[], metadata?: vscode.WorkspaceEditEntryMetadata): void {
-		this._editNotebookCellOutput(uri, index, true, outputs, metadata);
-	}
-
-	replaceNotebookCellOutputItems(uri: URI, index: number, outputId: string, items: NotebookCellOutputItem[], metadata?: vscode.WorkspaceEditEntryMetadata): void {
-		this._editNotebookCellOutputItems(uri, index, outputId, false, items, metadata);
-	}
-
-	appendNotebookCellOutputItems(uri: URI, index: number, outputId: string, items: NotebookCellOutputItem[], metadata?: vscode.WorkspaceEditEntryMetadata): void {
-		this._editNotebookCellOutputItems(uri, index, outputId, true, items, metadata);
-	}
-
-	private _editNotebookCellOutputItems(uri: URI, index: number, id: string, append: boolean, items: vscode.NotebookCellOutputItem[], metadata: vscode.WorkspaceEditEntryMetadata | undefined): void {
-		this._edits.push({ _type: FileEditType.CellOutputItem, metadata, uri, index, outputId: id, append, newOutputItems: items });
-	}
-
-	private _editNotebookCellOutput(uri: URI, index: number, append: boolean, outputs: vscode.NotebookCellOutput[], metadata: vscode.WorkspaceEditEntryMetadata | undefined): void {
-		this._edits.push({ _type: FileEditType.CellOutput, metadata, uri, index, append, newOutputs: outputs, newMetadata: undefined });
-	}
-
 	replaceNotebookCellMetadata(uri: URI, index: number, cellMetadata: vscode.NotebookCellMetadata, metadata?: vscode.WorkspaceEditEntryMetadata): void {
 		this._edits.push({ _type: FileEditType.Cell, metadata, uri, edit: { editType: CellEditType.PartialMetadata, index, metadata: cellMetadata } });
 	}