How to mark a To-Do as completed? 02 September 2015 06:16 Updated Please start in the 'Agenda' section. After To-Do is completed click the check box To unselect a To-Do activity click on the selected check box Related articles What is included in iCal export? How to clear completed To-Do's How do I share my calendar with the users on my account? How to view a contact's phone number from a call activity How do I edit a past activity?