Request/task &1 cannot be deleted because it contains locked objects

What causes this issue?

Request/task &V1& contains locked objects.

System Response

Request/task &V1& cannot be deleted.

How to fix this error?

If you want to delete the locked objects, expand the hierarchical
display until you can see the object list. Position the cursor on the
object and choose <LS>Delete</>.
You can then delete the request/task.
<ZH>Note:</>
Note the rules described in the warning message.
If the request/task contains a large number of locked entries, contact
the system administrator.
The Transport Organizer tools contain the function </>Requests/Tasks</>
-> <LS>Unlock Objects (Expert Tool)</>.
You can then delete the request/task.

Error message extract from SAP system. Copyright SAP SE.