It won't let you remove the last card because adding a card also unlocks some more "dangerous" apps that allow running custom code. And gives higher limits. Al

It won't let you remove the last card because adding a card also unlocks some more "dangerous" apps that allow running custom code. And gives higher limits. Alternatively add a disposable one-time card. Many fintech apps provide those. Still, as vendor, I'd avoid putting a random charge on your card and then pay the chargeback fee. Ouch.