I only have three users. In the user manager I see a check box next to each of the two users and none next to the administrator ID. That's normal.
To delete one of the users you select the check box for that user and go down to the drop down select box.
Problem: No drop down select box. I'm using 1.5.18.
Any suggestions? This is not a bridged system. The user manager should be able to make changes to the users.
Changed the permissions of a number of directories. That fixed it.