Remove wp_admin_bar fail on wordpress 4.0

by

You must use show_admin_bar(false); for disabling admin bar
to disable admin bar for all except admin add this to functions.php

add_action('after_setup_theme', 'remove_admin_bar');

function remove_admin_bar() {
if (!current_user_can('administrator') && !is_admin()) {
  show_admin_bar(false);
}
}

you can refer about that here