There are many ways to remove Admin Bar that popus up on every page since WordPress 3.1. You can use a plugin or manually edit some PHP files. But most of the sources (and users) forgets that the easiest way is to use proper setting in user profile (works only for frontend).
You can do this using one of these plugins:
Note: You can also use WP Custom Admin Bar (http://wordpress.org/extend/plugins/wp-custom-admin-bar/) plugin to change, what you see on Admin Bar instead of removing it completely.
Admin Bar removal can also be achieved by directly editing some WordPress PHP files. Refer to these pages for more information:
Most of these solutions, let's call them hard-ones, are aimed into completely removing Admin Bar from both backend (Dashbord) and frontend. Note, that if you only want to disable (hide) Admin Bar from your blogs (pages), when browsing it (frontend), but you want to keep it inside Dashbord, you can do this way easier.
Just go to your Blog Network configuration, to Users section, edit your own user (Super Admin) and uncheck "Toolbar: Show Toolbar when viewing site" checkbox. Repeat this for any other user, that you wish to hide frontend Admin Bar from.