function submitForm(array &$form, FormStateInterface $form_state)
 {
     $result = ManageStorage::fetchRowFields('id', $this->id, array('fid'));
     file_delete($result['fid']);
     ManageStorage::delete($this->id);
     drupal_set_message('CSV deleted successfully.');
     $form_state->setRedirect('node_csv_uploader.admin');
 }