How to close POs where old buyer does not exist.

Hi,

We have scenario where the current buyer of the PO does not exist, and we need to close this PO.

The setup at document types for security level is hierarchy. 

The other person in this hierarchy is not able to close this PO and getting the below error

' You Do Not Have Sufficient Authority To Control The Status Of this PO'

Is there any other way to close such POs, other than to change the setup for security level.

Thanks in advance,

Sheetal