Delete all product from cart in magento

I have add a function in the 

app\code\core\Mage\Checkout\controllers\CartController.php

add this function

public function deleteallAction()
    {
        $cartHelper = Mage::helper('checkout/cart');
        $items = $cartHelper->getCart()->getItems();      
        foreach ($items as $item)
        {
                $itemId = $item->getItemId();
                $cartHelper->getCart()->removeItem($itemId)->save();
        }
        $this->_redirectReferer(Mage::getUrl('*/*'));
    }