steps to reproduce:

live (root persistence)

user"demo" visits controlCentre::userManagement
and creates user"spock"

demo realizes"aw, spock should be assigned membership to a special 'crew' group"
so creates group"crew" and a new user account"spock2"

now, returning to the"delete" tab, in the userlist dropdown/selectbox, demo finds only these listed:
demo
spock2
spock2

(user"spock" is not listed)

=======================================

Out of curiousity, I added further users via the gui.
Each of 'em, I found them correctly listed in the selectbox and could successfully delete them...
...but"spock", the FIRST user account created via the controlCenter gui, _still_ is never listed.

did you go from the adduser tab strait to the remove tab? The version of user-management currently in antix 12 only populates the drop downs at application startup. So to bypass the issue, close usermanagement and reopen it. the newer version that i have made up should repopulate when opening the dropdown