If you want to purge closed sales or purchases that resulted in negative inventory

Closed sales or purchases that resulted in negative inventory can't be purged until a corresponding transaction that returns the inventory count to zero or greater is also entered in your company file.

For example, if you record a sale that results in a -2 for your inventory item Number 123, you must record a purchase for +2 or greater in order to purge the sale. If item Number 123 is an item you build, you could also build two of the items to return the inventory count to zero or greater; you could then purge the sale.