When you’re finished with a task, you can click the checkbox (to the left of the task title) to mark it as completed. This can be done directly from the task list or from the task pane.
Once you complete a task, it gets removed from your open tasks. If you want to reopen a completed task, you can do this as follows:
- Switch to Show Completed Tasks using the view selector
- Locate the task you want to reopen.
- Use the search functionality in the filter options to locate the correct task in case you have a lot of tasks
- Just click the checkbox to reopen your task