Yes, you can leave or delete a calendar from Calendar Settings:
Visit the Calendar options tab of the Calendar Settings page:
There are several options here:
If you leave a calendar that you do not own, you will simply stop having access to this calendar.
If you delete a calendar you own, all content inside this calendar will automatically and permanently get deleted. The calendar disappears from your dashboard, as well as from the dashboard of all your collaborators who had access to it.