To unassign a job from a person right-click on it and choose 'Unassign job'. The job will then move to the top of the schedule to the open shifts and jobs area. You can then assign it to another person if needed.
If a Job needs to be deleted from the schedule, this can be done if you right-click on it and choose 'Delete job'. This will open a pop up window to confirm if the Job needs to be deleted.