Sometimes one may want to hide the blogger banner, though personally i have felt the need for this Navigation bar. But in case you would love to hide this the following would be of help

To hide the Blogger Navbar :

1- Log in to blogger
2- On your Dashboard, select Layout. This will take you to the Template tab. Click Edit HTML. Under the Edit Template section you will see you blog's HTML.
3- Paste the CSS definition in the top of the template code:
Remove the code to show it again.


REFERENCES:- Blogger Templates