How do I change cardinality (delta) of nodes?
You can use form_alter hook to do it:

/**
 * Implements hook_form_alter().
 */
function your_module_form_alter(&amp;$form, &amp;$form_state, $form_id) {
  if ($form_id == 'article_node_form') {
    // Alter your field here:
    // $form['field_collection'][LANGUAGE_NONE][0]['value'];
  }
}


To debug form output, you can install Devel module and use dpm() function.

/**
 * Implements hook_form_alter().
 */
function your_module_form_alter(&amp;$form, &amp;$form_state, $form_id) {
  dpm($form);
}