how to remove add to cart button if price is 0 in magento 1?

I have done for call for price if price 0, But after that i want to remove add to cart button if price is 0.

<?php if ($  _product->getFinalPrice() == 0) : ?>                     <?php echo $  this->__('Call for Price') ?>                 <?php else: ?>                     <?php echo $  this->getPriceHtml($  _product); ?>                 <?php endif; ?>