If, for some reason, the project was canceled or you do not need to order products, you can delete the relevant draft purchase order (PO). Deleting is permanent; you cannot retrieve the deleted PO.
When you delete a PO, the products in the PO are moved to the "Ready to Order" item status and can be found in the "Procurement > Ready to Order" tab in the left navigation menu.
To delete a PO, go to "Procurement > Purchase Orders" in the left navigation menu. Click the 3-dot menu in the PO tile or row and click "Delete."
If you want to download a copy of the PO before deleting it, check out this article.