How to I prevent Facebook user from Full Admin access when RSVP to Event

I've added an event which I'm testing on a new blog.
http://amyragabha.com/events/2013/10/test-event/
When a user (my facebook account) RSVP, they get full Admin access to the blog site.
I need to understand how to restrict this when using the plugin. The person who RSVP shouldn't have any access to the backend interface or be able to change the event details.

Thanks
Harmeet