Order item & could not be deleted

What causes this issue?

The system cannot delete order item &V1&.
The reason for this may be that operations were manually added in the
original orders or the combined order.

System Response

The system terminates order combination.

How to fix this error?

Check whether operations were manually added to the original orders or
combined order.
If necessary, delete these manually added operations.
Then try to delete order item &V1& again.
If you still cannot delete the order item, contact you system
administrator.

Error message extract from SAP system. Copyright SAP SE.