This means that the incident was create due to failing job, which I assume is from a batch execution.
You can verify that in Batch view in Cockpit: https://docs.camunda.org/manual/7.10/webapps/cockpit/batch/monitoring/
In case you no longer need this failed batches and the respective jobs you can delete them and the incidents will be deleted with them.
It seems this API does not work. I’ve tried calling it in a variety of different ways including the way suggested and still the incidents are appearing in cockpit.