code: public AlertPolicyChannelService delete(long policyId, long channelId)
      {
          QueryParameterList queryParams = new QueryParameterList();
          queryParams.add("policy_id", policyId);
          queryParams.add("channel_id", channelId);
          HTTP.DELETE("/v2/alerts_policy_channels.json", null, queryParams);       
          return this;
      }
docs: Deletes the given alert channel from the alert policy with the given id.
  @param policyId The id of the alert policy from which to delete the channel
  @param channelId The id of the alert channel to delete
  @return This object