I think what you wanted to do was comment out the whole for loop like this

Code:
// build alpha sorter dropdown
  if (PRODUCT_LIST_ALPHA_SORTER == 'true') {
    if ((int)$_GET['alpha_filter_id'] == 0) {
      $letters_list[] = array('id' => '0', 'text' => TEXT_PRODUCTS_LISTING_ALPHA_SORTER_NAMES);
    } else {
      $letters_list[] = array('id' => '0', 'text' => TEXT_PRODUCTS_LISTING_ALPHA_SORTER_NAMES_RESET);
    }
    for ($i=65; $i<91; $i++) {
      $letters_list[] = array('id' => sprintf('%02d', $i), 'text' => chr($i) );
    }
//    for ($i=48; $i<58; $i++) {

// $letters_list[] = array('id' => sprintf('%02d', $i), 'text' => chr($i) );

// }