>>You may mark them somehow (I've seen prefixed them with asterisk, or greyed out) if 'deleted'. Or suffixed with "[discontinued]" or some such.
>
>I agree with your logic that since the items WERE used at some point, they have to be shown. And I will see how to "mark" these items differently.
>Thank you!

In some places of our software where we show hidden items we show them crossed out and in the red color.