Document &1, item &2 cannot be deleted

What causes this issue?

A document can only be deleted from the document stage assignment if it
is ONLY discharge-relevant.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

If you want to delete the document, you have to delete it from the
shipment.

Error message extract from SAP system. Copyright SAP SE.