Diagnosis
You want to remove delivery &V1& from a shipment.
However, items or shipping units of delivery &V1& have been packed in ashipping unit of the shipment.

System Response
You cannot remove delivery &V1& from the shipment.

Procedure
Unpack the items or the shipping units of delivery &V1& from theshipping units of the shipment.
Then you can remove delivery &V1& from the shipment.