It looks like you are using Ideal Responsive, or possibly Ideal Comfort as a skin.
The file you are looking to change is customer/main/cart.tpl
Look for a piece of code similar to this: {foreach from=$products item=product name=products}
This is likely the start of the foreach code that loops through the products in the cart.
Inside this foreach loop you should have a "<div class="price">" which is the div where the price is contained. You will probably see something similar to the following contained within:
Code:
{if $active_modules.Egoods and $product.distribution}1<input type="hidden"{else}<input type="text" size="3"{/if} name="productindexes[{$product.cartid}]" id="productindexes_{$product.cartid}" value="{$product.amount}" />
I'd remove the if statement and just keep the input field hidden. Just needs to be experimented with in this section.