Deletes forecasts from a machine learning job.
DELETE _ml/anomaly_detectors/<job_id>/_forecast
DELETE _ml/anomaly_detectors/<job_id>/_forecast/<forecast_id>
DELETE _ml/anomaly_detectors/<job_id>/_forecast/_all
By default, forecasts are retained for 14 days. You can specify a different
retention period with the expires_in parameter in the forecast jobs API. The delete forecast API enables you to delete one or more forecasts before they expire.

When you delete a job its associated forecasts are deleted.
For more information, see Forecasting the Future.
job_id (required)
forecast_id
_all, the
  API deletes all forecasts from the job.
allow_no_forecasts
false and there are no forecasts
  associated with the job, attempts to delete all forecasts return an error.
  The default value is true.
timeout
30s. For more information about time units,
  see Time units.
You must have manage_ml, or manage cluster privileges to use this API.
For more information, see Security Privileges.