Delete Sales Order Line item , change quantity of open items- OTC complete

Hi,

I have this scenario.

Sales order has been raised, partially delivered, Invoiced.

There are about 45 line items.

1. 2 line items which are not delivered at all, need to be deleted.

2. The quantity for 6 line items which are partially delivered(open items), needs to be changed to the quantity that is delivered.

Has someone faced this before? If so, what was the work around.

Thanks,