Need to disable/Grayed out Unreseve button for Order lines

Hi All,

In Back to Back order process once the order is progressed, the requisition will be created and Quantity will be reserved for PO to be received.
Some of our users want go and Unreserve this by the below methods.

1) Tools --> Scheduling --> Unreserve
2) Right Click on the order line --> Scheduling --> Unreserve

We need to Disable or Grayed out this Unreseve option for ATO Flagged lines.
Can anyone let me know if this is possible.

Thanks,
Praveen