Removing old domain email / alias

Removing old domain email / alias

Hopefully I can explain this without confusing everyone:

I have changed my domain name and the old domain is no longer used.  I have deleted that domain and added a new domain.  The administration login under my old domain was admin@xxxxxxxx.com.  I have created a new administration email address admin@xxxxxxxx.com for the new domain. 

Now here is where it gets wierd.  The old domain admin email address is an alias to the new admin email address.  It won't let me delete it. It tell me "input passed is invalid?" 

Any help would be appreciated.  I am about ready to delete account and start over!