code: def remove_item(self, jid, callback = None, error_callback = None):
          
          item = self.roster[jid]
          if jid not in self.roster:
              raise KeyError(jid)
          item = RosterItem(jid, subscription = "remove")
          self._roster_set(item, callback, error_callback)
docs: Remove a contact from the roster.
  
          :Parameters:
              - `jid`: contact's jid
              - `callback`: function to call when the request succeeds. It should
                accept a single argument - a `RosterItem` describing the
                requested change
              - `error_callback`: function to call when the request fails. It
                should accept a single argument - an error stanza received
                (`None` in case of timeout)
          :Types:
              - `jid`: `JID`