Form API Field Permission
I am already not try this but i think it will work 

function mymodule_form_alter(&amp;$form, &amp;$form_state, $form_id) {

  global $user;
  if ($form_id == 'FORM_ID') {
  if (in_array('yourrole', $user-&gt;roles)) {
  $form['your_field']['#access'] = FALSE;
    }
  }
}