Marvin lets you turn a task into a recurring task (or a project into a recurring project) with the Recur button in its details or Make recurring in its right-click menu. But how do you undo this and make it a normal task again?
Right-click any open copy of the recurring task or project and choose Duplicate (look under More if you don't see it). The copy is a normal task or project that isn't tied to the repeat. Then delete the repeat: open the main menu, click Recurring, and delete it there.
