Hidding a form element before printing
if you want to hide elements the appropiate way is to set the #access attribute on each element to FALSE, using a hook_form_alter()


  '#access'
  
  Used by: All elements and forms
  
  Description: Whether the element is
  accessible or not; when FALSE, the
  element is not rendered and the user
  submitted value is not taken into
  consideration.
  
  Values: TRUE or FALSE.


Source: http://api.drupal.org/api/drupal/developer--topics--forms_api_reference.html/7#access