prepu on "[Plugin: WooCommerce - excelling eCommerce] Don't show "add to cart" in one product"

I have a free downloadable product and when you click on that product you see the description and the number of products that you want to add to cart.
What I need is to remove that because I have already a download button in the short description area but I want to keep the "add to cart" in the rest of the products.
How can I do that?

http://wordpress.org/extend/plugins/woocommerce/