Get more sub level for in menu I'm able to get second level of the main menu by using below code.

$menu = '';
$menuItems = menu_tree_page_data('main-menu'); 
foreach($menuItems as $key =&gt; $m) {
    if ($m['link']['in_active_trail'] &amp;&amp; $menuItems[$key]['below']) {
        $menu = render(menu_tree_output($menuItems[$key]['below']));
   }  
}
print $menu;


If I want to get 3rd (like in image below), 4th or 5th level. how this will be done.
It is necessary that you want to display this using code?

I have a better solution for you. You can try with this module Menu Block for above achievement