>>265850
Open the file left4dead2/addonlist.txt. Every included addon has an image with the title, so to disable an addon, just browse the images in left4dead2/addons to find it, note the number in the filename, and change "1" to "0" next to the same number in addonlist.txt. Addons are supposed to include a manifest in the vpk for the game to read, so the few that don't show up correctly in the in-game addon menu.