you don't uninstall it. You just go into your BIOS at bootup by pressing delete key right away when you power on and in there will be an option to disable onboard video if it's there. That's all you need to do.
Also windows takes resources and such things like that, and it's not uncommon for an incorrect amount of RAM to be shown. I've known a lot of people including my own experiences where it says smaller than what I have, but your RAM technically never disappears. It's all there, just being used by something