Before you consider removing the admin bar, you should read this.

WordPress 3.1 was released earlier today and one of the key features is the admin bar, which allows you to get to your most-used dashboard pages with a single click. However, the admin bar is not for everyone and you can easily hide it by visiting your profile page.

You can also disable the admin bar for all users on your site by adding the following code to a plugin or the functions file of your theme:

add_filter( 'show_admin_bar', '__return_false' );

This will disable the admin bar for all users on your site but they will still see the admin bar preferences in their profile. You can hide the admin bar preferences using:

add_action( 'admin_print_scripts-profile.php', 'hide_admin_bar_prefs' );
function hide_admin_bar_prefs() { ?>
<style type="text/css">
	.show-admin-bar { display: none; }
</style>
<?php
}

Note: If you are using this code to only hide the preferences without disabling the admin bar, your users can still change the values by manually editing the hidden variables before the page is submitted.