// Disable XML-RPC
add_filter('xmlrpc_enabled', '__return_false');

// Remove the RSD link from the WordPress header
remove_action('wp_head', 'rsd_link');

// Disable X-Pingback HTTP header
add_filter('wp_headers', function($headers) {
    unset($headers['X-Pingback']);
    return $headers;
});

// Disable pingbacks
add_filter('xmlrpc_methods', function($methods) {
    unset($methods['pingback.ping']);
    return $methods;
});