I think there are a couple ways to accomplish this, but this is what I
use to remove the Navbar at the top of Blogger.

Go to Blogger
Click on Layout
Click Edit HTML
Scroll down the very bottom of the code
Copy and paste this code right BEFORE the </body> tag at the bottom

<style>
#navbar-iframe
{height:0px;
visibility:hidden;
display:none;}
</style>