You can manage your tasks by marking them when complete or removing them from the list when you no longer need to see them. You can edit tasks in any Tasks view. To see the tasks, even when complete, you must use another view besides the To-Do List view.
Click the Change View drop-down arrow.
Click Detailed.
Click the task you want to edit.
To mark a task as completed, click the check box in front of the task name, or click the Mark Complete button on the Home tab.
Outlook marks out the task.
To remove a task, click Remove from List.
You can also use the Follow Up tags to flag other date priorities for the task.