How to disable the WordPress Admin Bar

WordPress 3.1 introduces a new feature called the Admin bar. A lot of people will be wanting to disable this when WordPress 3.1 comes out. Since release candiate 2 you can disable it on a per user basis like this:

But since some people might want to disable the admin bar for everyone, I thought I'd show you a couple of ways to quickly disable the WordPress admin bar, either entirely, or just for you, or just for everyone else.

If you haven't seen it yet, the WP admin bar looks like this, and is added on top of all pages, on both the frontend and backend of your site, when you're logged in:

Disable Admin Bar for everyone

This one is reasonably simple, to disable the WordPress Admin Bar for everyone, add the following to your theme's functions.php file, the first bit hides the admin bar, the second bit hides the settings:

/* Disable the Admin Bar. */
add_filter( 'show_admin_bar', '__return_false' );

<?php function yoast_hide_admin_bar_settings() {
?>
	<style type="text/css">
		.show-admin-bar {
			display: none;
		}
	</style>
<?php
}

function yoast_disable_admin_bar() {
    add_filter( 'show_admin_bar', '__return_false' );
    add_action( 'admin_print_scripts-profile.php',
         'yoast_hide_admin_bar_settings' );
}
add_action( 'init', 'yoast_disable_admin_bar' , 9 );

Disable WordPress Admin Bar for specific requests

You might want to do this for specific requests only, so you can more easily take screenshots, for instance, then you add this to your theme's functions.php file:

if ( isset($_GET['bar']) && 'no' == $_GET['bar'] )
   add_filter( 'show_admin_bar', '__return_false' );

This would allow you to disable the WordPress admin bar by going to example.com/?bar=no, you can of course change those values.

Disable WP Admin Bar for specific users

To disable the WP Admin Bar, and the Admin Bar preference on his/her profile page for a specific user, add the following to your theme's functions.php file:

<?php function yoast_hide_admin_bar_settings() {
?>
	<style type="text/css">
		.show-admin-bar {
			display: none;
		}
	</style>
<?php
}

function yoast_disable_admin_bar() {
   if ( 2 == get_current_user_id() ) {
      add_filter( 'show_admin_bar', '__return_false' );
      add_action( 'admin_print_scripts-profile.php', 'yoast_hide_admin_bar_settings' );
   }
}
add_action( 'init', 'yoast_disable_admin_bar' , 9 );

Or you could do the reverse, and enable the WordPress Admin Bar just for one user, by disabling it for everyone else:

<?php function yoast_hide_admin_bar_settings() {
?>
	<style type="text/css">
		.show-admin-bar {
			display: none;
		}
	</style>
<?php
}

function yoast_disable_admin_bar() {
   if ( 2 != get_current_user_id() ) {
      add_filter( 'show_admin_bar', '__return_false' );
      add_action( 'admin_print_scripts-profile.php',
          'yoast_hide_admin_bar_settings' );
   }
}
add_action( 'init', 'yoast_disable_admin_bar' , 9 );

Update 7-1-2011: post updated after some remarks about current_user not being set yet at the point I was calling it, switched to using the proper __return_false helper function too, using the helpful comment from Cor van Noorloos in the comments.

Update 7-1-2011 - 2: post updated after an API change was decided upon and then implemented.