Hide your Quick launch

1.insert content editor webpart
  You can do it  in two ways
2.1.click Edit webpart.
   a.click "Click here to add a new content"
   b.Click "Format text"in the ribbon.
   c.Click "HTML" in the righ-hand side.
   d.paste the below code in th HTMl Editor and click ok
   E.Click "Apply" and "OK
   (or)
2.2.Copy and paste the code in your Editor(notepad,worpad,office).
   1.click "Site Setting"and select "View all site conten:
   2.Click "Site Assets"
   3.Upload the file.
   4.Copy the Url of the file.
   5.Now,insert "Content Editor" webpart
   6.click Edit webpart.
   7..click "Click here to add a new content"
   8.paste your URl in url column of the properties window.
   9.Click Apply and Ok
3.Now you must see the result.No quick launch on the site page.
Code to hide:
<style>
BODY #s4-leftpanel {
        DISPLAY: none
}
.s4-ca {
        MARGIN-LEFT: 0px
}</style>