If you're done using a gift card in your app, it's easy to delete. From the "My Cards" tab, switch to list view and tap the ••• icon to the right of the card name. Or, tap on the card you'd like to remove, and tap the ••• icon in the bottom right corner. There will be a delete option that you can select.
If you ever want to find the card info again, just login to your Raise account online and visit My Orders.