If your card is used for Family Sharing you cannot set it to none.
If you can‘t choose None when you edit your Apple ID payment information - https://support.apple.com/HT203905 - also make sure you don't have any active subscriptions, are set as the Family Organizer for a Family Sharing plan, or owe any money for past purchases.
If your card is used for Family Sharing you cannot set it to none.
If you can‘t choose None when you edit your Apple ID payment information - https://support.apple.com/HT203905 - also make sure you don't have any active subscriptions, are set as the Family Organizer for a Family Sharing plan, or owe any money for past purchases.
Changing/removing payment info : Change or remove your Apple ID payment information in the iTunes Store - Apple Support
If you don't get the 'none' option on the payment details screen : Why can’t I select None when I edit my Apple ID payment information? - Apple Support
how to take your card off of itunes and app payments
