What happens if delete a course from my calendar? Does this mean I’ve dropped the course?

Deleting a course from your calendar does not mean you have dropped the class.  You must drop the class via the Garnet Gateway.  Changes in your course schedule will appear following the next update.  Updates happen every 30 minutes.

If you delete a single course from your calendar, such as if that course is canceled for that period, it will reappear on your calendar the following morning after the system refresh.