cancel a backorder

Here is an example, we received an order for 130 pcs of an item. We shipped them 50 pcs that we have in stock at that time, and invoiced them the 50 pcs. There is a backorder of 80 pcs. They later decided to cancel the backorder. Do I just change from the OE the quantities from 130 to 50? Please advise.

Hello:
Edit the Order and change the quantity for that line item from 80 (Adagio shows the balance remaining) to 0 and post the Order.