I wish to show the hierarchical listing of groups using wordpress_list_groups but I wish to show just one category and it is subcategory

   <li ><a href="#">Main category</a>
    <ul >
     <li ><a href="#">Sub cat 1</a></li>
     <li ><a href="#">Sub cat 2</a></li>
        <li ><a href="#">Sub cat 3</a></li>

I attempted this code however it did not exercise

<?php wp_list_categories('include=19&depth=2&style=list&hierarchical=1&title_li=0&hide_empty=0'); ?>

Can anybody advise a solution?

You can test something similar to this:

$subcategories = get_categories('&child_of=4&hide_empty'); // List subcategories of category '4' (even the ones with no posts in them)
echo '<ul>';
foreach ($subcategories as $subcategory) {
  echo sprintf('<li><a href="%s">%s</a></li>', get_category_link($subcategory->term_id), apply_filters('get_term', $subcategory->name));
echo '</ul>';