If you screw up the Enterprise enrollment process:

* Log on to http://rhn.redhat.com
* View Systems | All
* Trash the errant system.

Go back to your server.
* As root, trash /etc/sysconfig/rhn/systemid
* Don't use the activation number, choose "Use existing account"
* Don't send your hardware profile.
* Re-register.  You should be nuts.