You can cancel job instances directly from the Dispatch Board. This will not cancel the master job. So, if you cancel a job from the dispatch board and it's a weekly job, the following week the job will still appear. To cancel a master job, please see this article.
To cancel a job on the Dispatch Board, simply check the box next to the job you want to cancel and hover over Actions and select "Cancel Job":
Remember that you can view cancelled jobs at any time on the Dispatch Board by applying the Status filter for "Canceled" jobs.