Prduction Order not getting Deleted

Dear Sir,

We created a Production Order and subsequently Released also . We confirmed activity also against this Order .

We are required to delete the Order now . We have cancelled the confirmed activity and now material is issued against the Order .

Now , when we try to mark the Order as "DELETED" in CO02 , then it is not getting marked Deleted .

Kindly guide us , as how can we DELETE the Production Order pl .

Regards

B Mittal