Switches the reminder off for the associated appointment.
true if the reminder has been successfully switched off; otherwise, false.
This method returns false for the reminder associated with a AppointmentType.Normal type appointment, if this appointment cannot be edited.
If the Dismiss is called for the reminder triggered by an appointment occurrence, then the reminder is set for the next occurrence in a chain and the method returns false. If the current occurrence is the last occurrence in a chain, the reminder is dismissed and the Dismiss method returns true.
For an infinite recurring series, this method will always return false.