Why in the world would you want to do that? Having a robust, but still an accessible website is what html is all about. And one of the requirements to meet is to build it responsive. If it's for testing purposes, I'll tell you how to do it. If your website, as a whole, is correctly built, all it would take to remove the "feature" (feature is not an adequate term, it should be a must) is to strip all the media queries for small resolutions (aka media for LINK, or @media, within your style sheet). If, on the other hand, your website "responds" via diverse and utterly useless js library and templating systems, such as twitter bootstrap and various grid systems that combine JS for nothing and endless pointless classes, swing an axe at it and start all over (WARNING : Do not try this at home. You may damage your computer and/or get hurt.). If, however, you want to "get rid of it", I didin't tell you that. You have read it online somewhere, but not in this thread.
I don't get you why you want to disable responsive mode in website as it is the latest trend these days as number of people using the smart phones are increasing considerably.
Honestly, I'm hoping the OP is mis-using the term and does not mean responsive layout, but something else...
http://11asgsm.ro/ Check the site in responsive mode and see why I want to disable it. The theme is responsive but I added some divs. I think it's better for me to learn how to configure these divs in a responsive mode so theme looks nice in all devices.