code: def remove_category(self, categories):
          
          categories = element_resolver(categories)
          diff = [category for category in self.data['category_child_ref']
                  if category not in categories]
          self.update(category_child_ref=diff)
docs: Remove a category from this Category Tag (group).
          
          :param list categories: categories to remove
          :type categories: list(str,Element)
          :return: None