How to mark a To Do as complete? March 30, 2015 15:27 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?