You can expire the roles for each user in the course. For example, when you click ENRL How do I add a student? How to modify student data. or CUSR (missing or broken file) on the remote control to add students, instructors, course coordinators into a course, you can set the ending date. When the ending date is reached, the role associated with the course will not be accessible to the user anymore.

If you go to the roles screen by clicking ROLES on the remote control, you will notice that there is a check box at the top where you can show all roles. If you check that box and then click display, you will see your current roles and your expired roles (if there are any).