Good question and I had to test it myself to be sure.
In the 7.x version,Yes they can make anyone a admin or delete them as a admin ,but they can't change the super admin.
Which in case you did not know is entered at:
Control Panel » Primary Settings{-}Advanced Options
Main Administrator User Id?
Which by the way sometimes needs to be changed via editing the config.inc.php file in cases where you are changing back to say yourself.
