Routing options for an Auto Attendant are determined by office hours schedules. As an administrator, you can delete an existing schedule, including one you added. The schedule is comprised of a series of events. An event is equal to a day of the week. The hours for each event reflect working hours for that day.
You can delete an office hours schedule for an Auto Attendant if you no longer need it. Weekly and yearly schedules are deleted in the same way.