If I'm not mistaken..
Admin rights are given per individual vs' rank.. when you go to "promote" someone there is a check box in the window that allows you to give them admin rights
though you can set certain ranks to have privilages as well .. none are truelly admin level though
WHile you can give "Full Admin Rights" to individual accounts, the Admin menu is also powered by Ranks, which you can set in the "Security > Feature Access" section of the Admin Menu.