Additional info key is still used. Cannot delete.

What causes this issue?

The selected <DS:DE.J_7LINFOK>additional info key</> is still used in
the REA master data.

System Response

The additional info key cannot be deleted.

How to fix this error?

First delete the additional info key from the REA master data. To do
this, choose REA Information Systems -> Assignment -> Article to ->
<DS:TRAN.J7LIZAR>Recycling Partner</> or Article to ->
<DS:TRAN.J7LIZAV2>Packaging (Recycling Partner-Dependent)</> or
Packaging to -> <DS:TRAN.J7LIZVR>Recycling Partner</>.
Instead of deleting, you can suppress the use of the additional info
key by deactivating it.

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.