How do you disable the admin-bar.css

This Should do the trick

<?php 
function adminBar_dequeue() {
    wp_dequeue_style('admin-bar');
    wp_deregister_style('admin-bar');
}

add_action( 'wp_enqueue_scripts', 'adminBar_dequeue', 9999 );
add_action( 'wp_head', 'adminBar_dequeue', 9999 ); 

?>