WordPress 3.1 introduced many new useful improvements, one of them being the admin bar.
However, for some websites the admin bar might be a little bit of an inconvenience. If this is the case for you then you can easily disable the admin bar from showing up by simply editing your user preferences.
On your dashboard just go to “Users”, select the user you want to disable the admin bar for and make sure you un-check the “when viewing site” box to hide the admin bar when you are viewing your actual website.

However, doing this requires having each user to manually hide the admin bar one at a time. This can be a very long and tedious process specially if you have dozens or hundreds of users.
Perhaps you’re running a membership website and you want to disable the WordPress Admin Bar for all users except administrators. If that is the case then I have something you are just going to love! Simply add the following code to your theme’s functions.php file:
/* Disable the Admin Bar for all but admins. */
if(!current_user_can('administrator')):
show_admin_bar(false);
endif;
If you want to disable the admin bar entirely for everyone, just add the code below to your themes functions.php file:
/* Disable the Admin Bar for everyone. */ show_admin_bar(false);
You could also a use a WordPress plugin called Disable Admin Bar that will do the same thing for you, but since you’re just copying and pasting into your functions.php file then you should have no need for the plugin.