If a customer want to restrict a payment method for particular store or all store, should have a options to Active / Inactive the payment method in All stores -> Payment methods.

Current process - Admin user can deleted the payment method against a store, If any transactions created against that payment type will restrict the deletions.

Limitations - No options to limit the payment method in conclude transaction button.

Improvements

* Admin can restrict this options at Store level, If this can be extended to register level, user can restrict payment methods at terminal level. It can helpful in case of customer is using mobile pos but don't want to use cash.