code: def deleteRating(self):
          
          url = "%s/deleteRating" % self.root
          params = {
              "f": "json",
          }
          return self._post(url,
                               params,
                               securityHandler=self._securityHandler,
                               proxy_port=self._proxy_port,
                               proxy_url=self._proxy_url)
docs: Removes the rating the calling user added for the specified item
          (POST only).