Disable, Remove Navigation Pane, Preview Sidebar in Windows 7
The navigation pane sidebar on the left of the windows 7 explore can be used to access files and folders quickly. This makes it easy to move or copy items directly to any destination in the navigation panel.
If you want to disable it or remove it click Organize, go to Layout, and then click Navigation pane to disable/enable it. Try working around with the Preview pane, Details pane to see if you want them or not.
You can also show hide rename items in Windows 7 explorer Navigation pane with Windows 7 Navigation Pane Customizer (link) which lets you add many useful locations to your left sidebar navigation pane.