Editing the payment method is available on your device.can always add, remove or edit your payment method.

Edit a payment method
1. On you iOS device, go to [Settings].
2. Select [Apple ID] > [iTunes and App Store]
3. Select [Payment & Shipping]
4. Select [Payment Method]
5. Select [None] or a different payment method
6. Fill in the necessary information and tap [Save]

In order to add or remove payment methods, please check the link below:
Change or remove your Apple ID payment information