Because the admin username if half the authentication pair to obtain administrative access to the server, it's probably not a good idea to publicize what is used currently, or what it might be in the future.
I suggest using something that makes sense for your organization, with "adm" or "admin" or "root" or "boss" in there somewhere, but going out of your way to not use the admin naming pattern used in training. You should, of course document this adequately, potentially in a locked cabinet to which management has a key, just in case.
The exam writing consultants hate the name "headless user", but I find it, from a security standpoint, better than publishing all data as user "BobJones" since he was the admin eight years (and three admins) ago. The publishing credentials should be closely held as well (and archived in the boss' lockbox), but not as closely as full-on admin privileges.
- V