Scan the card using your phone's NFC or QR reader, or use the computer NFC Reader
Open the card's webpage in your browser

Login with your Admin account
Search and select the user to whom you want to assign the card.

The card will appear on the user's page.

Navigate to the user's page and locate the cards section.

Click on the card you want to remove
Click "Delete card"

You can now reuse this card.