Ok, I found the Scale with pixel aspect ratio, or something like that in the NVIDIA control panel. My second question is a lot more complicated, I don't know if it's even possible.
The reason I only wanted to disable some of my pixels is because almost a fourth of the right part of my screen has died (dead pixels). Now, after scaling, I have a centered desktop with two black bars at the sides. Can I make the desktop align to the left so both that black bars are to the right?