Hi There, If you go into the PO via ME21N and select the item detail and the delivery tab you can complete the PO by setting the delivery complete flag. Hope this helps. The proper Transaction is ME23N (Display Purchase Order) not ME21N. ME21N is Create Purchase Order. Remember, you must be in Edit Mode to check off “Delivery Complete” on the Delivery Tab in Item Detail.
The Tcodes ME21N, ME22N and ME23N are for create, change and display Purchase order respectively. You don’t have to create the PO. You can ME23N. In ME23N, you can simply complete delivery flag. It will be closed.