Hi,
To pay with a PayPal account, you want to use the normal PayPal integration, and thus configure the PayPal Checkout payment plugin.
There is no mechanism to hide the credentials only. However, once you configure your payment and shipping methods, you can go in the "Access level" tab of the HikaShop configuration and disable access to the "Plugins" area for all the user groups. That way, no one will be able to access that area. Also, the HikaShop configuration is only available to super users by default, so normal users of the backend won't have access to it either.