To remove an alarm, launch iHealth MyVitals and go to:
MENU > Set up my devices > Select your AM3 > Sleep alarm or Active alarm.
Press and hold the alarm to be deleted. Then press again on the alarm to delete it.
*credit to Sylvain of iHealth Labs EU
https://helpcenter.ihealthlabs.eu/hc/en-gb/articles/205766682-iHealth-AM3-Delete-an-alarm