Canceling Purchase Orders 
Prerequisites
The purchasing process is complete.
The purchase order has not yet been drawn (fully or partially) to a higher level purchasing document, such as a goods receipt PO or A/P invoice.
Procedure
1. From the SAP Business One Main Menu, choose 
Purchasing – A/P 
Purchase Order 
, and find the relevant purchase order.
2. In the menu bar, choose Data Cancel .
Result
The status of the purchase order changes to Canceled. The purchase order itself is not deleted. You can still display and duplicate it, but you cannot change it or draw it to a higher level purchasing document.