Xbox One Subscription.

The Gold Subscription will transfer to Xbox One and the subscription will be good regardless if you log on to your Xbox 360 or your Xbox One.

To remove your card first cancel any renewing subscriptions here:
https://account.microsoft.com/services/ "Cancel automatic renewal".

Then you can remove it here:
https://account.microsoft.com/billing/payments

If that first link has an amount in red with "pay now" beside it, that's an overdue payment and it must be paid first before anything else can be done.

Also, if you are thinking about using currency stored in your account (microsoft account balance), that can not be used for xbox live gold or game pass. You must use a credit/debit/bank account/paypal for that purchase. You can use that balance for games
and addons, though.

Hello! As long as you have any active subscriptions you have to have credit card or paypal account on file as payment, even if it's just as a backup payment method.

They can just sign into their existing accounts and use it that way. You wouldn't need to buy anything.

The Gold subscription requirement has been in place for four years, since Games With Gold was expanded to Xbox One. Xbox 360 GWG titles are still yours to keep forever, even if your subscription lapses, and can still be installed and played on Xbox One.
Xbox One GWG titles require you to maintain an Xbox Live Gold subscription; if you let your subscription lapse, you would have to buy the games outright, or renew your subscription.