How do we Remove payment method

Did you already have a look at these related articles, to make sure that your payment information is complete and correct?

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

If you have ongoing subscriptions, you will have to add a new payment method first, before you can remove the old one.

Roblox appears to be a game platform with artificial consumables ("Robux") that you pay for with real money (in-app purchases).

https://apps.apple.com/us/app/roblox/id431946152

Go to your settings and then go to wallet and Apple Pay… then you can change your payment method….