How can we return a PO which is linked with Work order operation

Summary:

We have an OSP item where PO has been created and materials are received. Now Business needs to return that PO, but when we checked in Supplier operations tab Return to Vendor and other options are greyed out. The corresponding WO operation shows completed.

We were looking to reverse the completed OSP operation through dispatch list page, but that operation is not showing there.

Can anyone help here on how we can return the corresponding PO?

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