You can find information on how to cancel the card on this page.

Note that cancelling the card does not cancel any subscription on the card. If you wish to end a (train) subscription, you should contact NS customer service directly. This can be done by phone; they are available 24/7 at 030-751 51 55. You may also try to contact them by chat (click the link Chat with NS on this page) or by sending a message on Twitter or Facebook.

Note that after contacting customer service to end your subscription you need to confirm this at a ticket machine. Customer service will inform you about this. Don't forget this step, as the cancellation of the subscription will not be complete until you do so.

If you are unable to complete this last step, for example because you are abroad, then make sure to explicitly mention this to customer service. They can then end the subscription in a different way, removing the need to confirm it, but then the card can no longer be used for another NS subscription in the future.