roundcubemail/program/lib/Roundcube/rcube_storage.php
public function unset_flag($uids, $flag, $folder = null)
    {
        return $this->set_flag($uids, 'UN'.$flag, $folder);
    }
public function unset_flag($uids, $flag, $folder = null)
    {
        return $this->set_flag($uids, 'UN'.$flag, $folder);
    }
public function unset_flag ( $ uids , $ flag , $ folder = null ) { return $ this -> set_flag ( $ uids , 'UN' . $ flag , $ folder ) ; }
Remove message flag for one or several messages

@param mixed  $uids    Message UIDs as array or comma-separated string, or '*'
@param string $flag    Flag to unset: SEEN, DELETED, RECENT, ANSWERED, DRAFT, MDNSENT
@param string $folder  Folder name

@return bool   Operation status
@see set_flag
Remove message flag for one or several messages