2 emails in admin account

[pppplus]

Hi,

I have a small problem, but ennoying...

I have my admin emails account 2 times.

Si I have :
[email protected], login : admin
[email protected], login : admin@mydom

1st in the main one, 2nd is probably here after restoring a backup.

If I try to delete the 2nd one, I have message that it is impossible to delete main account...

Have you an idea to delete this account ?