$aElement['strip'] = array(
      '#type' => 'image_button',
      '#button_type' => 'button',
      '#src' =>'sites/all/modules/flexifield/images/strippable.png',
      '#value' => t('Delete this record'),
      '#weight' => 1,
      '#ahah' => array(
        'path' => 'flexifield/ahah/deleteone/' .$aElement['#type_name']. '/' .$aElement['#id']. '/'. implode(':', $aElement['#array_parents']). '/'. implode(':', $aElement['#parents']),
        'wrapper' => $aWrap . '-items',
        'method' => 'replace',
        'effect' => 'fade',
      ),
    );

$aItems['flexifield/ahah/deleteone'] = array(
   'file' => 'flexifield-widget.inc',
   'page callback' => 'flexifield_ahah_deleteone',
         'access arguments' => array('access content'),
         'type' => MENU_CALLBACK,
 );

//...
  $form_state = array('submitted' => FALSE);
  $form_build_id = $_POST['form_build_id'];
  $form = form_get_cache($form_build_id, $form_state);
  if (!$form) {
    // Invalid form_build_id.
    drupal_json(array('data' => ''));
    exit;
  }
  $form_copy = $form;
  $form_state_copy = $form_state;
  $form_copy['#post'] = array();
  form_builder($_POST['form_id'], $form_copy, $form_state_copy);
  // Just grab the data we need.
  $form_state['values'] = $form_state_copy['values'];
  // Reset cached ids, so that they don't affect the actual form we output.
  form_clean_id(NULL, TRUE);
  //...here change $form_state according the task
  $form_element = content_field_form($form, $form_state, $field);
  // Let other modules alter it.
  drupal_alter('form', $form_element, array(), 'flexifield_deleteone_js');
   // Add the new element at the right place in the (original, unbuilt) form.
  if (module_exists('fieldgroup') && ($group_name = _fieldgroup_field_get_group($type['type'], $field_name))) {
    $form[$group_name][$field_name] = $form_element[$field_name];
  }
  else {
    $form[$field_name] = $form_element[$field_name];
  }

  // Save the new definition of the form.
  $form_state['values'] = array();
  form_set_cache($form_build_id, $form, $form_state);
  // Build the new form against the incoming $_POST values so that we can
  // render the new element.
  foreach ($_POST[$field_name] as $delta => $item) {
    if($delta!==$iKey){
        $i = $i+1;
        if($delta>$iKey){
          $_POST[$field_name][$delta-1] = $item;
        }
     }
   }
   unset($_POST[$field_name][$count]);
   $form_state = array('submitted' => FALSE);
   $form += array(
    '#post' => $_POST,
    '#programmed' => FALSE,
   );
   $form = form_builder($_POST['form_id'], $form, $form_state);
   // Render the new output.
   $field_form = (!empty($group_name)) ? $form[$group_name][$field_name] : $form[$field_name]; 
   $render = drupal_render($field_form);
   drupal_json(array('status' => TRUE, 'data' => $render));