<?php

/**
 * Implements hook_element_info_alter().
 */
function mymodule_element_info_alter(&$type) {
  if (isset($type['text_format'])) {
    $type['text_format']['#process'][] = 'mymodule_process_format';
  }
}

function mymodule_process_format($element) {
  global $user;

  //hide for all except superadmin
  if ($user->uid <> 1) {
    hide($element['format']);
  }

  return $element;
}