If a recurring appointment is to be changed for one date, simply click on that date and either edit it or drag it to a new time/date. If all future recurring appointments need to be changed, edit the appointment, and select Edit the series radio button, then set the current recurrence to an end date. Then make a new recurring appointment for the future date. To delete one recurring appointment, click on the appointment and select Delete.  To delete all future recurring appointments, click on the first date you want deleted and selected Delete all future recurring.