code: def delete_metadata(self, loadbalancer, keys=None, node=None):
          
          if keys and not isinstance(keys, (list, tuple)):
              keys = [keys]
          md = self.get_metadata(loadbalancer, node=node, raw=True)
          if keys:
              md = [dct for dct in md if dct["key"] in keys]
          if not md:
              # Nothing to do; log it? Raise an error?
              return
          id_list = "&".join(["id=%s" % itm["id"] for itm in md])
          if node:
              uri = "/loadbalancers/%s/nodes/%s/metadata?%s" % (
                      utils.get_id(loadbalancer), utils.get_id(node), id_list)
          else:
              uri = "/loadbalancers/%s/metadata?%s" % (
                      utils.get_id(loadbalancer), id_list)
          resp, body = self.api.method_delete(uri)
          return body
docs: Deletes metadata items specified by the 'keys' parameter. If no value
          for 'keys' is provided, all metadata is deleted. If 'node' is supplied,
          the metadata for that node is deleted instead of the load balancer.