Here’s a quick reusable way to hide the left navigation.

 Create a text file called “HideLeftNav.txt” in a document library.

 Add the following css code:
<style type=”text/css”>
/*–Hide Quick Launch –*/

 Edit the page you want to hide the nav on, add a content editor webpart. Then, simply reference the url to the HideLeftNav.txt file and you are done.