Cannot set deletion flag for product cost collector &1

What causes this issue?

The deletion flag cannot be set for product cost collector &V1& for one
or more of the following reasons:
There are still run schedule headers for the product cost collector in
which the status <LS>Deletion indicator</> is not set.
There are production versions for the product cost collector in which
the status <LS>Deletion indicator</> is not set.
There are postprocessing records in repetitive manufacturing that are
to be assigned to the product cost collector.
There are manufacturing orders for the product cost collector in which
the status <LS>Deletion indicator</> is not set.

System Response

The system does not set a deletion flag.

How to fix this error?

Check the status of the orders assigned to the product cost collector.
To display the orders and production versions assigned to the product
cost collector, select <LS>Goto -> Display orders</>.

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.