But they will still keep your credit card number forever if you ever give it to them. Once it's been added, it can't be removed. They claim it's for auditing

But they will still keep your credit card number forever if you ever give it to them. Once it's been added, it can't be removed. They claim it's for auditing purposes, but those "auditing purposes" shouldn't require keeping it attached to the account as an active payment method (which is what they enforce).