A user given Administrators permissions via ACP > Permissions > Administrators and then given the "Create new user" permission has it indefinitely and can't be selected > "Remove Permissions" to remove them.
After I uninstalled the mod to see if it would help, the above screenshot happened. It shows acl_a_add_user now, and no matter how many times I select "No" and click "Apply Permissions", it always comes back as "Yes".
Unfortunately, I can't seem to duplicate this on my WAMP phpBB forum, so it seems isolated to this one forum. If anyone knows of a fix or could direct me to the database table where I can forcibly remove these users I'd appreciate it.