public function down()
 {
     $root = User::find()->where(['email' => '*****@*****.**'])->one();
     $root->delete();
     $admin = User::find()->where(['email' => '*****@*****.**'])->one();
     $admin->delete();
     $user = User::find()->where(['email' => '*****@*****.**'])->one();
     $user->delete();
 }
 public function down()
 {
     $auth = \Yii::$app->authManager;
     $rootUser = User::find()->where(['email' => '*****@*****.**'])->one();
     $adminUser = User::find()->where(['email' => '*****@*****.**'])->one();
     $root = $auth->getItems('root');
     $admin = $auth->getItems('admin');
     // Assign roles to users. 1 and 2 are IDs returned by IdentityInterface::getId()
     // usually implemented in your User model.
     $auth->revoke($root, $rootUser->id);
     $auth->revoke($admin, $adminUser->id);
     $auth->removeItem($root);
     $auth->removeItem($admin);
 }