I makes no sense, and I really hope that you cannot do this. A scroll bar appears when your content does not fit the page vertically or horizontally. And the user of the site has every right to make the size of the browser window as she/he likes. Preventing it would be a big abuse. This "requirement" is wrong in principle because it aims to limit natural user's writes to access you content.
You should think in completely different direction: to make your page layout tolerant to window size. I designed this sophisticated query :-) for you to look for appropriate techniques:
This is really what you should look for.