my server cant change ulx groupallow superadmin

ok so i entered in my console rcon ulx groupallow superadmin rope, anyway i check my srcds console and it says

Sorry, for security reasons, you can’t change the access of the superadmin group

i read ulx thingy and it says you must used a dedicated server console, so i typed in the srcds console

ulx groupallow superadmin rope
and it comes up again

Sorry, for security reasons, you can’t change the access of the superadmin group

You need to use the text files.

what text files though? whats the name of them