- A (parent)
  - B (child of A)
    - C (child of B)
- X (parent)
  - Y (child of X)
    - Z (child of Y)

$args = array(
    'hide_empty'         => 0,
    'orderby'            => 'name',
    'order'              => 'ASC',
    'show_count'         => 0,
    'use_desc_for_title' => 0,
    'echo'               => false,
);
$categories = wp_list_categories($args);