how to add re-order to wp user panel of wordpress?

You can re order admin left menu by below code:

/*
 * Code below groups Dashboard/Posts/Pages/Comments together at the top of the dashboard menu.
 * If you were to have a custom type that you want to add to the group use the following edit.php?post_type=YOURPOSTTYPENAME
 */
function reorder_my_admin_menu( $__return_true ) {
    return array(
         'index.php', // Dashboard
         'edit.php?post_type=page', // Pages 
         'edit.php', // Posts
         'upload.php', // Media
         'themes.php', // Appearance
         'separator1', // --Space--
         'edit-comments.php', // Comments 
         'users.php', // Users
         'separator2', // --Space--
         'plugins.php', // Plugins
         'tools.php', // Tools
         'options-general.php', // Settings
   );
}
add_filter( 'custom_menu_order', 'reorder_my_admin_menu' );
add_filter( 'menu_order', 'reorder_my_admin_menu' ); 

Above code used custom_menu_order and menu_order hook to re order existing menu items. Hope this help you well!

tech