$permission = 1,$registration = null
これは何をやっているんでしょうか?
以下加筆↓
public function admin_change_permission($id,$permission = 1,$registration = null){
$park = $this->Prak->findById($id);
if($permission == 0){
$this->Park->updateAll(['Park.permitted_flag' => $permission],['Park.id' => $id]);
$this->Flash->success('非掲載にしました');
return $this->redirect(['action' => 'index']);
}