Hi,
If you want to completely change the menus in the control panel, then you should remove the foreach code and replace it with your own HTML yes.
The quantity button is displayed in the administrator/components/com_hikashop/helper/cart.php in the displayButton function.
Instead of editing the code there directly, I would recommend instead to create a template override for your modifications:
www.hikashop.com/en/support/documentatio...tation.html#override
That will allow you to update HikaShop while still keeping your modifications in place.