public function drop($key)
    {
        if($this->has($key)) {
            unset($_SESSION[$this->root][$key]);
            return true;
        }

        return false;
    }
public function drop($key)
    {
        if($this->has($key)) {
            unset($_SESSION[$this->root][$key]);
            return true;
        }

        return false;
    }
public function drop ( $ key ) { if ( $ this -> has ( $ key ) ) { unset ( $ _SESSION [ $ this -> root ] [ $ key ] ) ; return true ; } return false ; }
Clear value in session

@param string $key
@return bool
Clear value in session