If you use the default template of Blogger.com , of course there is a navbar on top of the template (navigation bar).
Have you ever wondered what it is used for ? It is not very nice for your blog, its work just allow you go to edit and go to next blog faster..., but if you are a pro webmaster, this is very uncomfortable and useless.
So I will lead you how to let it go in many ways
1st way: not allow it to appear
2nd way : Set its height = 0
3rd way: Hide Navbar
Then choose 1 of the 3 CSS code above and copy + paste correctly before tag </head> in "Edit HTML"
The last way : Hide navbar
copy this code and paste it right before tag </head> :
You can try any way but the last way is the best result to make it disappear.
Good luck to you.
If it is still standing on your blog, pliz contact me.