I have a load of mods in my settings menu, some of which were uninstalled several years and two vBulletin versions ago. The mods themselves are uninstalled, they're no longer in the Product Manager, but they do clutter up the general Settings menu.
Some of them are so old that's not possible; others have expired licenses, or the person/company selling them is no longer around, or I simply can't find the mod any more. It's a bit of a pickle!