I agree that this feature is needed. In addition to having unnecessary campaigns in a person's page it creates confusion in the group, because the GM does not know who is active in the group. Players join groups, because they think that they are interested in the game (and this is great, this is how groups of new people get created), but after a session or two person decides that the game or schedule is just not for him/her. Now it is difficult to politely and respectfully opt out of the group. You cannot even e-mail the GM unless you happened to ask him for his address. The only way out is to request via a post in the game's campaign discussion to have the GM boot you from the group and hope the GM sees the post.