You may receive a Purchase Order with multiple Line Items. You cannot cancel items on the Item Level in the Purchase Order. If you cannot fulfill one of the Line Items you must cancel the entire Purchase Order.
Use the "Cancel" action button to cancel the entire Purchase Order. Ask your retailer to send a separate order for the item you can fufill.
If you have any questions about partial fulfillments or order cancellations please contact Logicbroker at Support@Logicbroker.com.