It sounds as if you are asking for ability to edit the payment methods accepted through your payments account.
Unfortunately, there isn't a way to make changes to the pay methods available with your merchant account. Merchant services open up the freedom to accept major credit cards Visa, MasterCard, Discover, and American Express (AMEX)*.
If you need to disable the option to pay by credit card on an invoice, you can deselect the option when creating the invoice.
For accounts that do not have AMEX as a payment method, it can be added within the Merchant Service Center under Account Profile.