The following two has the same effect. The job will be removed/unscheduled/deleted.
Your must first get the Schedular instance.
scheduler = schedFact.GetScheduler();
Unschedule the Job (basically removes the trigger and hence the job)
scheduler.UnscheduleJob(new TriggerKey("Job1Trigger", "Group1"));
Remove the trigger as well as the job.
scheduler.DeleteJob(new JobKey("Job1", "Group1"));
Both has the same effect. The syntax is actually incorrect on Quartz.net site where they are missing the new operator.