I want to disable all types of sounds permanently so the user will not be able to hear any kind of sound in future.
I have uninstalled sound drivers from Device Manager, but on restarting PC they get automatically installed again.
Don't delete the drivers, Disable them instead. They stay installed but not used. Right click on the sound devices and select disable - They should all be under 'Sound, Video and Game controllers' (Windows 7/8)