This might be not proper approach but this worked for me while testing.
You can use these combinations to remove all links from Toolbar (admin-bar ) and then hide empty tool bar with css:
function remove_admin_bar_links() {
global $wp_admin_bar;
$wp_admin_bar->remove_menu('wp-logo'); // Remove the WordPress logo
$wp_admin_bar->remove_menu('about'); // Remove the about WordPress link
$wp_admin_bar->remove_menu('wporg'); // Remove the WordPress.org link
$wp_admin_bar->remove_menu('documentation'); // Remove the WordPress documentation link
$wp_admin_bar->remove_menu('support-forums'); // Remove the support forums link
$wp_admin_bar->remove_menu('feedback'); // Remove the feedback link
$wp_admin_bar->remove_menu('site-name'); // Remove the site name menu
$wp_admin_bar->remove_menu('view-site'); // Remove the view site link
$wp_admin_bar->remove_menu('updates'); // Remove the updates link
$wp_admin_bar->remove_menu('comments'); // Remove the comments link
$wp_admin_bar->remove_menu('new-content'); // Remove the content link
$wp_admin_bar->remove_menu('w3tc'); // If you use w3 total cache remove the performance link
$wp_admin_bar->remove_menu('my-account'); // Remove the user details tab
}
add_action( 'wp_before_admin_bar_render', 'remove_admin_bar_links' );
function hide_admin_bar() { ?>
<style type="text/css">
#wpadminbar {
display: none;
}
</style>
<?php }
// on backend area
add_action( 'admin_head', 'hide_admin_bar' );
// on frontend area
add_action( 'wp_head', 'hide_admin_bar' );
For more details read this link
Out put is like below screenshot:
