Product cost collector &1 cannot be deleted

What causes this issue?

You cannot delete product cost collector &V1& as there are still APO
orders which assign to it.

System Response

The deletion flag is not set.

How to fix this error?

Only delete a product cost collector once all orders which assign to it
have been deleted.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.