If you’ve got a lot of add-ons, you probably have a bit of clutter in the browser Paths menu. Like this:
You can get rid of all those add-ons by cleaning out the Addons/InstalledAddons folders in your User and Workgroup locations. Softimage checks those folders (at startup) to build the list of add-ons for the Paths menu.
Don’t worry; removing the .xsiaddon files from the InstalledAddons folder doesn’t uninstall the addons.