Bug: Handle organizer deleting account with upcoming events

[ParthZee]

Summary

Organizer should not be able to delete their account if they have upcoming events.

Expected Behavior

Either:

• Prevent deletion until all events are cancelled or completed, OR
• Automatically transfer or cancel the events.

Current Behavior

• Currently cancels all the events associated with that organizer and marks their bookings for refund (but who will actually pay the refund amount?)