[Lynne]

Open /includes/config.php and enter your userid in place of the red x:

    //    ****** UNDELETABLE / UNALTERABLE USERS ****** 
    //    The users specified here will not be deletable or alterable from the control panel by any users. 
    //    To specify more than one user, separate userids with commas. 
$config['SpecialUsers']['undeletableusers'] = 'x';