Delivery Complete indicator and PO Release

Dear All,

My PO has been approved and the release indicator is released no Change which means user cant change the PO, now in case i have received partial delivery and supplier didnt commit to delivery the remaining Qty, in this case i need to set PO items as complete delivery, but once i m in ME22n system issue message "Purchasing document has release indicator Y (changes not possible)", is there away to change the PO wizout changing the configuration of release procedure.