A user had question about two options to remove tasks from the To-do List:
What is the difference between "Remove from List" and "Delete" in Outlook's To-Do List? It seems redundant to me.
The source of your confusion is both Delete and Remove from List are available for Tasks on the Home ribbon (but not on the right click menu) and with actual Tasks, they both do the same thing - delete the selected task.
They are not redundant with flagged messages on the To-Do List. You'll use Remove from List to remove follow up flags from flagged Outlook items; it's the same as Clear Flag (on the right-click Follow up menu) when you use it on flagged items. If you delete the flagged message from the To-do list, you'll delete the message from your mailbox too.
If you need to keep your task history, mark the task Complete and use a filtered view, such as Active tasks, to hide completed tasks. When you need to view these tasks, switch to either the Completed view or Simple list view.
The user also wanted to know how to view task that were removed from the list:
How can you see tasks you have removed?
When you delete or remove a task from the list, the task is moved to the Deleted Items folder. If you know the task subject or other information, you can search the deleted items folder for it, otherwise turn off the reading pane then sort by the icon column to see all deleted tasks together. You can add additional fields (such as Completed, Flag complete date, Follow up flag, and Modified date fields) to the view then group by these fields (and collapse all groups) to more easily view the deleted items.
Select Simple list from the Current view selector (expand it to select Completed) or use the View tab, Current view menu.
If you remove a flag from a message using Clear flag or Remove from List, you won't have a record of the item being previously flagged. If you need to keep a history of flagged messages, mark the message flag Complete and use a filtered view in the To-Do List to hide the completed items.