Go to your Blogger template

You can see this code

-----------------------------------------------
Blogger Template Style
Name:     Rounders
Designer: Douglas Bowman
URL:      http://www.ndogmu.com
Date:     27 Feb 2004
Updated by: Blogger Team
----------------------------------------------- */

Put this code:

#navbar-iframe {
   display: none !important;
}

After that

Now your nav blogger will dissapear