There are 3 ways to switch off the alarm.
24-Hour Alarm Reset - Press the Power button when the alarm goes off if you want to stop the alarm immediately but also want to keep the same alarm setting for the next day
Repeat Alarm - When the alarm goes off, press Repeat Alarm/Brightness Control to repeat the alarm at 9-minute intervals
Cancel the Alarm Completely - Press the ALM 1 or ALM 2 button one or more times until ALM1 or ALM2 disappears