Disable AJAX in a form
Ajax behavior is attached to form elements when there is a record in Drupal.settings.ajax for the HTML-id of the form element. Therefore in order to disable Ajax for a given form-element, you need to remove the appropriate ajax settings record. You can achieve that by implementing hook_js_alter:

function hook_js_alter(&amp;$javascript) {
  foreach ($javascript['settings']['data'] as $index =&gt; $item) {
    foreach ($item as $key =&gt; $settings) {
      if ($key == 'ajax') {
        // The prefix id for a field_collection with the name fc:
        $field_id_prefix = 'edit-field-fc-und';

        // Remove ajax settings for the "Add another item" button
        unset($javascript['settings']['data'][$index][$key][$field_id_prefix . '-add-more']);

        // If you also need to de-ajaxify the "Delete" buttons:
        foreach (array_keys($settings) as $element_id) {
          if (preg_match('/' . $field_id_prefix . '-[0-9]+' . '-remove-button/', $element_id)) {
            unset($javascript['settings']['data'][$index][$key][$element_id]);
          }
        }
      }
    }
  }
}