Sub-Page display problem

I am having a problem with which sub-pages display on my site.

If you go to https://fenderbluesjunioramps.com/accessories-parts-mods you will see the following sub pages of “Mods, Parts, & Extras”:
Speakers
Tubes
EL84 Tubes
12AX7 Tubes
Footswitches
Soft Cover
Hard Case
Knobs
Reverb Tanks

The problem is that “EL84 Tubes” and “12AX7 Tubes” are sup pages of “tubes” and i don’t want them to display on the “Mods, Parts, & Extras” page (current page). I ONLY want them to show up once “tubes” is clicked.

Here is the current PHP code. what can i change to fix this? thanks so much!:

<?php 

if ($aOptions['show_subpages']) :

global $id;
$aSubPages = get_page_children($id, '');
if (count($aSubPages) > 0) :

?>
<div id="child_pages">
<h3>More Pages</h3>
<ul class="icon jump">
<?php foreach ($aSubPages as $page) { echo('

<li><a>guid . '">' . $page->post_title . '</a></li>
'); } ?>
</ul>
</div>

thanks!!!