Magento : add massDelete action in coupon code

First override Mage_Adminhtml_Block_Promo_Quote_Grid class and add following code
protected function _prepareMassaction()
    {
        $this->setMassactionIdField('rule_id');
        $this->getMassactionBlock()->setFormFieldName('rule');

        $this->getMassactionBlock()->addItem('delete', array(
             'label'    => Mage::helper('rule')->__('Delete'),
             'url'      => $this->getUrl('*/*/massDelete'),
             'confirm'  => Mage::helper('rule')->__('Are you sure?')
        ));
         return $this;
    }


then override Mage_Adminhtml_Promo_QuoteController class and add following code
public function massDeleteAction()
    { //exit;
        $rulesIds = $this->getRequest()->getParam('rule');
        if(!is_array($rulesIds)) {
             Mage::getSingleton('adminhtml/session')->addError(Mage::helper('adminhtml')->__('Please select rule(s).'));
        } else {
            try {
                $model = Mage::getModel('salesrule/rule');
                foreach ($rulesIds as $rulesId) {
                //echo $rulesId; exit;
                    $model->load($rulesId);
                    $model->delete();
                }
                Mage::getSingleton('adminhtml/session')->addSuccess(
                    Mage::helper('adminhtml')->__(
                        'Total of %d record(s) were deleted.', count($rulesIds)
                    )
                );
            } catch (Exception $e) {
                Mage::getSingleton('adminhtml/session')->addError($e->getMessage());
            }
        }

        $this->_redirect('*/*/index');
    }