Coding help...

unistar

I am using (what I think) is one of the best GPL carts out there: osCommerce. I'm a newbie to PHP code and I need some help (i've tried editing, commenting code out, but it's not working)...
The code creates a vertical menu listing that displays categories. When you click on one it shows the subcategories below that (it displays subcategories in the middle of the page by default so I don't need subcategories showing on the menu also).
What I need is that once you click on the category it will not display the subcategory below...

function tep_show_category($counter)
{ global $foo, $categories_string, $id;
for ($a=0; $a<$foo[$counter]['level']; $a++)
{ $categories_string .= " "; }

$categories_string .=

'<img src="http://"';
if ($foo[$counter]['parent'] == 0)
{ $cPath_new = 'cPath=' . $counter; }
else { $cPath_new = 'cPath=' . $foo[$counter]['path']; }

$categories_string .= tep_href_link(FILENAME_DEFAULT, $cPath_new);
$categories_string .= '">';
if ( ($id) && (in_array($counter, $id)) ) 
   { $categories_string .= '<font color=red><strong><u>'; }

// display category name
$categories_string .= $foo[$counter]['name'];
if ( ($id) && (in_array($counter, $id)) )
{ $categories_string .= '</strong></u></font>'; }

if (tep_has_category_subcategories($counter)) 
   { $categories_string .= ''; }

$categories_string .= '</a>';
if (SHOW_COUNTS == 'true') 
   { $products_in_category = tep_count_products_in_category($counter);
  if ($products_in_category > 0) {
   $categories_string .= ' (' . $products_in_category . ')'; } }

$categories_string .= '<br>';
if ($foo[$counter]['next_id']) {
  tep_show_category($foo[$counter]['next_id']); } } ?>

<tr><td><?php
$info_box_contents = array();
$info_box_contents[] = array('align' => 'left',
'text' => BOX_HEADING_CATEGORIES );
new infoBoxHeading($info_box_contents, true, false);
$categories_string = '';
$categories_query = tep_db_query("select c.categories_id, cd.categories_name, c.parent_id from " . TABLE_CATEGORIES . " c, " . TABLE_CATEGORIES_DESCRIPTION . " cd where c.parent_id = '0' and c.categories_id = cd.categories_id and cd.language_id='" . $languages_id ."' order by sort_order, cd.categories_name");
while ($categories = tep_db_fetch_array($categories_query)) {
$foo[$categories['categories_id']] = array(
'name' => $categories['categories_name'],
'parent' => $categories['parent_id'],
'level' => 0,
'path' => $categories['categories_id'],
'next_id' => false
);

if (isset($prev_id)) {
  $foo[$prev_id]['next_id'] = $categories['categories_id']; }

$prev_id = $categories['categories_id'];
if (!isset($first_element)) 
   { $first_element = $categories['categories_id']; } }

//------------------------
if ($cPath) {
$id = split('', $cPath);
reset($id);
while (list($key, $value) = each($id)) {
$new_path .= $value;
unset($prev_id);
unset($first_id);
$categories_query = tep_db_query("select c.categories_id, cd.categories_name, c.parent_id from " . TABLE_CATEGORIES . " c, " . TABLE_CATEGORIES_DESCRIPTION . " cd where c.parent_id = '" . $value . "' and c.categories_id = cd.categories_id and cd.language_id='" . $languages_id ."' order by sort_order, cd.categories_name");
$category_check = tep_db_num_rows($categories_query);
while ($row = tep_db_fetch_array($categories_query)) {
$foo[$row['categories_id']] = array(
'name' => $row['categories_name'],
'parent' => $row['parent_id'],
'level' => $key+1,
'path' => $new_path . '' . $row['categories_id'],
'next_id' => false );

    if (isset($prev_id)) 
       { $foo[$prev_id]['next_id'] = $row['categories_id']; }

    $prev_id = $row['categories_id'];
    if (!isset($first_id)) { $first_id = $row['categories_id']; }
    $last_id = $row['categories_id']; }

if ($category_check != 0)
{ $foo[$last_id]['next_id'] = $foo[$value]['next_id'];
$foo[$value]['next_id'] = $first_id; }

  $new_path .= '_'; } }

tep_show_category($first_element);
$info_box_contents = array();
$info_box_contents[] = array('align' => 'left',
'text' => $categories_string );
new infoBox($info_box_contents);
?></td></tr>