There is a setting in iOS to disable it... Settings > Notifications > down at the bottom there's a Government Alerts section, with AMBER Alerts and Emergency A

There is a setting in iOS to disable it... Settings > Notifications > down at the bottom there's a Government Alerts section, with AMBER Alerts and Emergency Alerts toggles. At least, there is with AT&T, because I recall getting a notification saying my phone's software was updated to be complient with phone company requirements, which added the two toggles.