// configuration adjustments for 'dev' environment
$config['bootstrap'][] = 'debug';
$config['modules']['debug'] = [
 'class' => 'yii\debug\Module',
 // uncomment the following to add your IP if you are not connecting from localhost.
 //'allowedIPs' => ['127.0.0.1', '::1'],
];

namespace app\libs;

use Yii;

class Tools
{
 public static function DebugToolbarOff()
 {
  if (class_exists('\yii\debug\Module')) {
   Yii::$app->view->off(\yii\web\View::EVENT_END_BODY, [\yii\debug\Module::getInstance(), 'renderToolbar']);
  }
 }
}

use app\libs\Tools;

……

public function actionIndex()
{
 Tools::DebugToolbarOff();

 return $this->render('index');
}