You can also remove sub menus. You can find the sub menu names in wp-admin/menu.php

 
function remove_submenus() { 
 
global $submenu;
unset($submenu['index.php'][10]); // Removes 'Updates'.
unset($submenu['themes.php'][5]); // Removes 'Themes'.
unset($submenu['options-general.php'][15]); // Removes 'Writing'.
unset($submenu['options-general.php'][25]); // Removes 'Discussion'.
} 
add_action('admin_menu', 'remove_submenus');