You can disable the sound card! That means NO SOUND at all, it won't even think it has a sound card
Go into Control Panel and open up Device Manager, find your sound card, right click, and Disable. There you go, no sound, and no idiot, not even a smart idiot, will be able to get it back on.
Don't try to uninstall it though, it may sound promising to uninstall so the idiot would have to find drivers and all, but the problem is, if you uninstall then Windows will see it as a new device, automatically install drivers for it, and it'll be working again.