How can I exclude subcategories from category navigation on homepage?

Hi,
How can I exclude subcategories from category navigation on homepage?
In header.php file I see the code,
but I can’t to do it.

<?php
/*to exclude some categories */
$args = array();
/* $args = array(
‘exclude’=> array( get_cat_ID(‘aciform’), get_cat_ID(‘alignment’), get_cat_ID(‘antiquarianism’)) // exclude by category slug
‘exclude’=> (1, 2, 3) //exclude by category id
); */
$categories = get_categories($args);

$categories = get_categories();
foreach($categories as $category):
?>