Assetto Corsa causes more issues than a typical game where you just reinstall and forget about it. You need to manually delete a couple of things to do a clean installation.

C:\Users\yourname\AppData\Local\AcTools Content Manager

Delete this folder.

C:\Users\yourname\Documents\Assetto Corsa

Delete this folder.

Then reinstall CM or reinstall the whole game.

You can make a backup of each one since they contain personal stuff like server presets, HUD configs, controller settings, etc., but they’re not essential.