I actually had this problem a while ago - my mobo sound was shot, and I was trying to get rid of the drivers. In my case, I simply installed a Creative Sound card whose drivers overrode the ac97 ones. If you're planning on installing anthing to replace your mobo sound, you don't really need to remove the drivers - just make sure your pc doesn't use the ac97 as a sound source anymore. If you just want to remove the drivers, I would assume you would remove the ac97 in the device manager.