We have a scenario where the available balance for an inventory item has hit zero, and the latest reservation for that item has gone into BACKORDER.

This WO for which the reservation went to BACKORDER is relatively urgent, and cannot wait for stock replenishment.

Is there a way by which we can get any of the earlier reservations (APHARD) for this item (on other WOs) be released so that this urgent WO can progress?

In a way you are looking for a way to change/release an APHARD reservation correct ? 

We have a scenario where the available balance for an inventory item has hit zero, and the latest reservation for that item has gone into BACKORDER.

This WO for which the reservation went to BACKORDER is relatively urgent, and cannot wait for stock replenishment.

Is there a way by which we can get any of the earlier reservations (APHARD) for this item (on other WOs) be released so that this urgent WO can progress?