I’m trying to remove a payment but it can’t remove

Possible reasons:

1. If you have an unpaid balance or payment due
2. If you have a subscription that automatically renews

• View your purchase history to see your recent purchases and find out which order is unpaid
• Try on a computer 

After the unpaid balance is paid, you can remove your payment method

See:

If you can't remove your last payment method or use no payment method with your Apple ID

https://support.apple.com/en-ca/HT203905

.