If the export button is temporarily displayed, you should import the iCalender file (.ics) into a separate new (temporary) calendar, as you can simply delete it, because changes are common on this stage. Two weeks after the start of the semester you can import the iCalender file (.ics) into your calendar, as it is now unlikely that something will change in the timetable.
If you've imported an iCalender (.ics) file and you want to delete it, you may have to do this manually. You should therefore only export it if it's finalized.