You can archive this document. Following check criteria should match for purchase orders:
HI Khushbu ,
You cannot delete a PO from the header level if it has been already sent to the supplier. Check the logs in output message to see if its been output. In case it not been output , you can delete the PO at the header level and the status of the PO would become 'deleted'. Otherwise you will have to delete the line item , or if follow-on documents exists then either decrease the PO quantity or place the final delivery and final invoice indicator.
Please confirm which report you are running.