If you don't need a calendar anymore, you can permanently delete it. Note that once you deleted a calendar, all its events will be deleted as well, and there is no undo action available.
If you want to delete a calendar:
1. Select the calendar that you want to delete and click [Go].
2. Then, click on the [Create new] button.
3. On the “Delete Calendar” section, make sure the correct calendar is selected, and click [Delete].
4. The system will prompt a message to confirm the delete action. Click [OK] to proceed.
5. The calendar will be deleted. Click [OK] to go back to the calendar application.