I do not have an active subscription but I still cannot remove my existing payment method. for your advise please

If you can't choose None when you edit your Apple ID payment information

1. If you have an unpaid balance or payment due
2. If you have a subscription that automatically renews
3. If you're using the iTunes Store or App Store for the first time
4. If you are not in the country or region you’re creating an Apple ID for
5. If you changed your country or region
6. If you're a part of Family Sharing