SysAdmin account shows at login, but doesn't work and is not listed in Users & Groups

Colin.inBelgium wrote:

When I start my MacBook Air (Mojave), I see the correct list of accounts from which to choose.

If I choose my SysAdmin account, it accepts the password correctly, the horizontal progress bar advances to the end and then it redisplays the login screen with the list of available accounts - but MINUS the SysAdmin account.

If I logon with another account which has admin privileges and look in Users & Groups, I see all the accounts listed, minus the non-functioning SysAdmin account. I see the same list of accounts in Users & Groups, with no SysAdmin account listed, if I don't try to logon to the SysAdmin account first.

I have created a new Administration account (with a slightly different name), which works fine. 

How do I remove the non-working SysAdmin account from the account list that appears when I start my Mac, as I can't find a way to see it in the User & Groups list?

I have tried using "sudo dscl . create /Users/SysAdmin IsHidden 0" just in case the account became hidden in Users & Groups.

This will list all registered users on you computer,

From the command line, copy and paste:

dscl . list /Users | grep -v '_'

And this admin account is problematic somehow, independent of trying to delete it?

https://medium.com/@ambroselittle/cant-delete-original-https://discussions.apple.com/thread/8087348

ref:

Can't delete admin user in High Sierra

https://discussions.apple.com/thread/8087348