To turn off Optional Alarms*, go to Menu -> Alarms -> (select the alarm you want to turn OFF) -> Toggle to OFF -> Done. The Urgent Low Glucose Alarm is mandatory and cannot be turned OFF.
* Notifications will only be received when alarms are turned on and the sensor is within 33 feet unobstructed of the reading device. You must enable the appropriate settings on your smartphone to receive alarms and alerts, see the FreeStyle Libre 3 User's Manual for more information.