Stuff

I have a stack class that has a pop function like so...
     /**
     * Pop the Stack.
     * @returns mixed The reference to the popped element.
     */
     function &pop() {
         $element = &$this->top();
         array_pop($this->_stack);
         return $element;
     }

It seems to be returning the reference to the popped element, but how do I access the actual value of the element.

Also after construction an object like so, $mystack=new Stack, how do I destruct it so it does not take memory when i no longer need it.