A payee must have at least one payment type saved for them. You can remove all of the payment types from a payee, however when you remove the final payment type it will delete the payee.
Please note that if you’d like to replace all the existing payment type/s for a payee with new payment type/s, you’ll need to add a new payment type before deleting all of the old payment types to avoid deleting the payee.
If a payment type is no longer valid or no longer represents the payee that you’ve assigned it to then you should remove the payment type to avoid accidentally addressing a payment to it in the future.
If you can’t remove a payment type it is likely to be because you have future dated payments scheduled to it. To remove the payment type you’ll need to cancel any future dated payments you’ve scheduled to it.