Releasing Encumbrance from Partially Received/Invoiced PO

Dear,

We have a requirement to partially close PO's and release related encumbrances.

Scenario :

PO Qty = 1000

Received Qty = 800

Invoice Matched = 800

Now in funds inquiry 200 still showing in encumbrance. This balance we have to release.

Which of the following is best solution to close PO's and release encumbrances:

1. Finally close PO - will this change order qty to matched invoice qty. We do not want original PO quantity to be changed. else we have to view PO Change history option

2. Cancel PO Line (along with PR) - This will reduce qty order and shows zero qty and price and PO line level. which seems to be incorrect. else we have to view PO Change history option