If all your likers are not showing up on
Settings -> People and Other Pages
an alternate way to handle the flood of content that you don't want might be to use their posts to remove them.
Each reply you get has an 'X' on the RHS. If you click on that it will Hide the comment. Then it will display several options where the reply used to be displayed:-
Unhide Delete Report Ban <name>
You can then click to Ban that person.
This will only work for comments, not likes, but it will clean up any of the active users on your page that you don't want. Those that only like and don't comment are perhaps less of a worry anyway?
Good Luck!.