Re: [Koha] Local use preference OPACviewMARC doesn't switch off?

It is, however, listed under the Local use tab.

I somehow missed this part of your original message. Preference can show up under Local use if they're not officially part of Koha. If you had a customization at one time which included that preference it would make sense that it is still around even if the customization is long gone. It's not part of Koha. -- Owen