Hide SharePoint 2010 Quick Launch Menu

Edit the page by clicking Site Actions ➪ Edit Page.

Place your cursor in the main content area, and then click Insert ➪ Web Part from the ribbon.

From Categories, select Media and Content, and from Web Parts, select Content Editor, and then click Add

Insert Web Part in SharePoint 2010 

Select the web part and go to HTML Editor

Hide Quick Launch in SharePoint 2010, Edit HTML  

Copy this code and past it same as what you see in the image

<style type="text/css">
/*--Hide Quick Launch --*/

Hide Quick Launch in SharePoint 2010

Click Ok

From the tool pane on the right, expand Appearance, change Chrome Type to None, and then click OK.

From the ribbon, click Save & Close to save the page.