If you invite people from your neighborhood to paint a mural on your garage door, you ought to be free to paint over some of it if you decide that don't like what some of them have done. It is your garage door, after all, and everyone that came over knew that when they started.

You don't have a right to post whatever you want on someone else's server. And if that somehow wasn't clear to you, Rackspace's terms of service spelled that out explicitly.