bbp_remove_forum_id_from_all_groups( type $forum_id )

function bbp_remove_forum_id_from_all_groups( $forum_id = 0 ) {

	// Validate
	$forum_id  = bbp_get_forum_id( $forum_id );
	$group_ids = bbp_get_forum_group_ids( $forum_id );

	// Loop through groups and remove this forum from each one
	foreach ( (array) $group_ids as $group_id ) {
		bbp_remove_forum_id_from_group( $forum_id, $group_id );
	}
}