Remove the whole menu in the admin

How can i remove the whole menu in the admin?

I have this code:

function remove_menu_items() {
    global $menu;

    end( $menu );

    while ( prev($menu) ) {
        $value = explode( ' ', $menu[ key($menu) ][0] );
        if ( $value[0] != NULL ? $value[0] : "" ) {
            unset( $menu[ key($menu) ] );
        }
    }
}
add_action( 'admin_menu', 'remove_menu_items' );

This only removes the default menu items, any pages added to the menu by a plugin are still there.

How can i remove the whole menu?

add_action('admin_head', 't5_hide_menu');
function t5_hide_menu()
{
    $GLOBALS['menu'] = array();
    ?>
<style>#adminmenuback,#adminmenuwrap{display:none !important}
#wpcontent, #footer{margin-left:0 !important}</style>
<?php
}

Now I want to know: why? 🙂