PIN codes' maintenance is performed in the PIN Codes tab of the related product details page.
Here, a store admin can see a list of sold PIN codes created both automatically and manually. For manually created PIN codes, the list also contains items in-stock. A store admin can delete manually created PIN codes if they have not been sold.
PIN codes in the list can have either a Sold or Blocked status with a link to the order in which this product was purchased. A Blocked status means that the related order is waiting for payment.