Unfortunately according to my experience you can't. Once the invitation for a multiclub arena has been accepted you cannot withdraw. You may not participate but the club will still be registered to the arena. In one of the clubs I administrate we call the invitation "the Nuclear Button" because we can't undo anything if we press it. It becomes a problem when there are too many admins and not all know about the button so they press it accidentally.
Multi club arena - how a club can to leave?

Unfortunately according to my experience you can't. Once the invitation for a multiclub arena has been accepted you cannot withdraw. You may not participate but the club will still be registered to the arena. In one of the clubs I administrate we call the invitation "the Nuclear Button" because we can't undo anything if we press it. It becomes a problem when there are too many admins and not all know about the button so they press it accidentally.
Thanks! Gracias Pablo.
Hello! I would like to know how a club can to leave a multi club arena?