Sometimes the WordPress admin toolbar simply gets in the way. Usually when working on design work or if you just want to view your site how a visitor would see it removing the admin bar is a must.

Paste the following code in your header.php file just below wp_head();.

<style>
   html { margin-top: 0 !important; }
   #wpadminbar { display: none; }
</style>

This code will not remove the admin bar from the DOM, but it will not be visible or take up any space so by all means it is removed. If this proves to be helpful enough I will convert this into a plugin which will allow you to show/hide the admin bar by activating/deactivating the plugin. Rather than having to add code directly to your theme.