/**
  * Delete All notifications from a
  * defined category
  *
  * @param $category_name int
  * @param $expired Bool
  * @return Bool
  */
 public function deleteByCategory($category_name, $expired = false)
 {
     $query = $this->notification->whereHas('body', function ($q) use($category_name) {
         $q->where('name', $category_name);
     });
     if ($expired == true) {
         return $query->onlyExpired()->delete();
     }
     return $query->delete();
 }