AFAIK, you can't delete the administrator account anyways and even with a rename (simply security through obscurity), it can be found. Tools like SID2USER and USER2SID (I think that's what they are called) can help with this.

That said, I don't think it can be done since there are so many tasks that require admin specifically (GID 500 that is). It'd be like deleting root on a *nix box. I can't imagine that one would be able to do it since even booting requires root.