add_action('wpf_tags_modified', 'my_wpf_delete_user', 5, 2);

function my_wpf_delete_user($user_id, $user_tags) {

    if( in_array( 'TAG NAME', $user_tags ) && ! user_can( $user_id, 'manage_options' ) ) {
        wp_delete_user( $user_id );
        wp_die();
    }

}