src/vs/workbench/api/browser/mainThreadComments.ts/MainThreadCommentController/deleteCommentThread
class MainThreadCommentController:	deleteCommentThread(commentThreadHandle: number) {
		let thread = this.getKnownThread(commentThreadHandle);
		this._threads.delete(commentThreadHandle);

		if (thread.isDocumentCommentThread()) {
			this._commentService.updateComments(this._uniqueId, {
				added: [],
				removed: [thread],
				changed: []
			});
		} else {
			this._commentService.updateNotebookComments(this._uniqueId, {
				added: [],
				removed: [thread as MainThreadCommentThread<ICellRange>],
				changed: []
			});
		}

		thread.dispose();
	}