How to remove console access from a player?

I have a "friend" who I gave access to the website console cause he said he wanted to be able to launch the game by himself, and now he has started cheating multiple times, can someone help me out with removing his access to the console?

also I tried deoping, and banning him, but because he has access to the whole server with the console he can just unban himself, and my only option is to delete the world