Payment Type(s) are the different ways a customer pays for the purchases made. For example, Cash, Credit Card, etc. All payments are made at the Web Register.
You will not be able to delete a Payment Type that has data associated with it.
The payment options will vary for a Walk-in-Customer and a Registered Customer. For walk-in customers the payment can be processed either in Cash or Credit Card or Gift Card. For registered customers, additional options like Loyalty, Store Credit and On-Account are enabled.
This article with video helps you get acquainted with the steps to create and delete payment types in Tagrain.