Reversal of Order posting

We have done order GR with 101 movement. Material is inspection managed, so 04 insp type insp lot created. QI clear lot and posted stock in unrestricted by mistake, b'se we suppose to cancel this order.

Now QI reverse inspection lot stock posting and UD. Stock is back again in QI. Now we want to reverse order. What is procedure? Order status is TECO DLV CNF

Actually this order is created from SO, make to order scenario. So our final goal is reject SO.