https://userapps.support.sap.com/sap/support/knowledge/en/2112365
2112365 - BBP_PD 730 error occurs when deleting all the PO item | SAP Knowledge Base Article
When there is no ordered version exists for a PO. If all the items of the PO are deleted , error Message BBP_PD 730 : "Deleted items cannot be ordered" occurs.