How to Kill A Job Once it's Triggered in the Queue?

I have a job in AEM that implements JobConsumer interface. My questions are:

1. Once it's triggered but not running yet, how to kill the job? 

2. Once it's running, how to kill the job?

I saw JobConsumer interface has `cancel` method but I am not sure how to use it. I found an example online and it's not using cancel() in the exception clause:

    @Overridepublic JobResult process(Job job) {
        try {
            logger.debug("Processing the JOB *******");

            //A Property map will be passed on so we can fetch the values we need here to//Process the request

            String path = (String) job.getProperty("path");
            logger.debug("The path in which the replication is triggered and passed to the Job is " +
                    "{}", path);

            //TODO : Write your business logic here . Any properties you need to execute the job can be passed//TODO: on via the  Map which is treated as the properties for the JOB.


            /**
             * Return the proper JobResult based on the work done...
             *
             * > OK : Processed successfully
             * > FAILED: Processed unsuccessfully and reschedule --> This will keep the JOB up for next retry
             * > CANCEL: Processed unsuccessfully and do NOT reschedule
             * > ASYNC: Process through the JobConsumer.AsyncHandler interface
             */return JobConsumer.JobResult.OK;
        } catch (Exception e) {
            logger.error("Exception is ", e);
            return JobResult.FAILED;
        }
    }
}