Hi,
Add to cart buttons are automatically removed everywhere if you turn on that option. The only reason I can think of it wouldn't work would be that your template has custom views for HikaShop which override the default views and these overrides don't take this option into account.
So rename temporarily the folder templates/YOUR_TEMPLATE/html/com_hikashop via FTP in order to deactivate all the view overrides of your template. If the add to cart buttons disappear after that, it means that it indeed comes from your template and I would recommend to contact your template provider for help customizing their view overrides.