Remove payment details

Somtetimes you cannot remove a payment method because you'll need to have at least one payment method on file.

If you're in need of updating your payment method, please see this instructions

Update your payment method on your iPhone or iPad

1. Open the Settings app.
2. Tap your name.
3. Tap Payment & Shipping. You might be asked to sign in with your Apple ID.
4. Tap Add Payment Method, enter the new payment method, then tap Done.
5. Tap Edit.
6. Tap the red delete button next to the old payment method, then tap Delete.

See this Link for further reference

If you need to change or update your Apple ID payment method - Apple Support