If someone's being unruly in one of your rooms, you have the option to ban them from the room. You can also ban players from any rooms to which your friends have granted you moderation rights.
Ban a player from any room to which you have moderation privileges by tapping on their avatar and then tapping “Kick from room” in the small black popup menu right above your chatbox.
Be careful who you kick from your rooms! Once players have been banned from a room, it’s permanent. While you can always unblock, you cannot unban players from rooms.