Codeigniter在注销时删除cookie？

我正在我的codeigniter网站上实现记住我的功能。我试着用饼干来做。当登录时选中“记住我”时，将创建cookie。我正在删除注销时的cookie功能。但由于某些原因，cookie不会被删除。请帮帮我

登录功能代码的控制器部分

if(empty($this->input->cookie('username'))){
   echo "cookie empty";exit;
   $this->load->view('admin/login');                
} else if(!empty($this->input->cookie('username'))) {   
  echo "cookie not empty ".$this->input->cookie('username');exit;           
  $userdata=$this->welcome_model->getloginwithUsername($this->input->cookie('username'));
  $user_role=$this->welcome_model->getUserRole($userdata->id);
  $session['id']=$userdata->id;
  $session['username']=$userdata->username;
  $session['email']=$userdata->email;
  $session['contact']=$userdata->contact;
  $session['department']=$user_role->department;
  if($role->department=='retailer'){
    $session['brand']=$user_role->brand;
  }                 
  $this->session->set_userdata($session);
  redirect(dashboard);              
  //$this->load->view('admin/login');
}

function logout()
{       
   $array_items = array('username', 'email','contact','id');
   $this->session->unset_userdata($array_items);        
   $this->session->sess_destroy();
   $this->load->helper('cookie');
   delete_cookie('id');
   delete_cookie('username');
   redirect(ADMIN); 
}

控制器注销功能代码

if(empty($this->input->cookie('username'))){
   echo "cookie empty";exit;
   $this->load->view('admin/login');                
} else if(!empty($this->input->cookie('username'))) {   
  echo "cookie not empty ".$this->input->cookie('username');exit;           
  $userdata=$this->welcome_model->getloginwithUsername($this->input->cookie('username'));
  $user_role=$this->welcome_model->getUserRole($userdata->id);
  $session['id']=$userdata->id;
  $session['username']=$userdata->username;
  $session['email']=$userdata->email;
  $session['contact']=$userdata->contact;
  $session['department']=$user_role->department;
  if($role->department=='retailer'){
    $session['brand']=$user_role->brand;
  }                 
  $this->session->set_userdata($session);
  redirect(dashboard);              
  //$this->load->view('admin/login');
}

function logout()
{       
   $array_items = array('username', 'email','contact','id');
   $this->session->unset_userdata($array_items);        
   $this->session->sess_destroy();
   $this->load->helper('cookie');
   delete_cookie('id');
   delete_cookie('username');
   redirect(ADMIN); 
}