You can modify existing schedules by opening the Schedule module and double-clicking on the schedule you want to change (or right-clicking and selecting ‘View/edit schedule…’).
You can then change the schedule criteria (Start date, end date, recurrence pattern, etc.), as well as the item and task list information.
Once you’ve made all the required changes, you can then Save your changes. Alternatively, if you’ve made a mistake, you can Cancel your changes. If the schedule is no longer required, you can also permanently Delete schedule.