It sounds like you're trying to delete your primary calendar (the first
one that's listed under "My Calendars"). As you've seen, you can't
actually delete your primary calendar like you can your other
calendars- clicking on the trashcan icon will remove the events from
your primary calendar, but not actually delete the calendar itself.
This is how Google Calendar currently works. Once you've deleted the
events from your primary calendar, you can start adding new events to
this calendar and perform other actions on this calendar shortly after
clicking on the trashcan.
Feel free to let me know if you're having trouble deleting a secondary
calendar and I'll take a further look into the matter.
