Only customer services can remove a card from a closed paypal account unfortunately.
Contact options for each countries Paypal customer services are accessed by clicking help/contact bottom left of Paypal pages.
1. Paypal phones when available (you can use the guest option if you can't log in). 2. Live chat is also randomly available. 3. You can send them a message, during business hours you may also be able to message whilst logged out. Or 4. Have you considered contacting Customer Service via Facebook or Twitter? You can send them a personal message from their Facebook or Twitter pages. It's: https://www.facebook.com/PayPal and @AskPayPal for Twitter.
Advice is voluntary. Kudos / Solution appreciated.