I'm guessing you will always want 1 as the quantity so heres how to do it
in skin1/customer/main/product.tpl .... change:
Code:
<select id="product_avail" name="amount"{if $active_modules.Product_Options ne '' && $product_options ne ''} onchange="check_wholesale(this.value);"{/if}>
{section name=quantity loop=$mq start=$start_quantity}
<option value="{%quantity.index%}" {if $smarty.get.quantity eq %quantity.index%}selected{/if}>{%quantity.index%}</option>
{/section}
</select>
to:
Code:
<input type="hidden" id="product_avail" name="amount" value="1">