There is no way to do that unless you were seriously messing with files under the C:\Windows directory, in which case you can expect weird things to happen. Can be fixed by repairing or reinstalling your OS.
I know a way to enable/show admin account and to hide/disable it. This the first time i heard/know it can be deleted....
Could u give a detail about it... and any effect it having (after it deleted)...
btw: I hope this not asking a way to breach admin pass/security thread.... we cannot help u in that
If you're on a corporate network, Group Policy may have renamed it (but not deleted it). If you boot the machine in Safe mode, it may very well "re-appear."
Sounds kinda sketchy to me, I think Windows requires there to be at least one administrator account, I think what he is trying to do is recover one that he has access to, which can be used to access a computer that is not yours.