How disable authentication bar for users?

Hi myt007,

It seems you’re asking about to hide the admin bar appears at the top when user is logged in.
If this is something you want, then add the following code in your theme’s functions.php file

<?php
// Checks if currently logged-in user is not admin
if ( ! current_user_can( 'manage_options' ) ) {
 show_admin_bar( false );
}
?>

The above code is for when users are logged in except admin, then admin bar will not be shown them.
But if you want to hide the admin bar for all including admin, then just need to add the following code:

<?php
show_admin_bar( false );
?>

Hope this will help you.