iOS
Turn off alerts for the subscriber
Go to the Flight Alerts widget > tap on Subscriber
How to Delete the subscriber
You can do it in two ways:
1) Go to the Alerts widget > tap and hold the Subscriber's icon
Select Delete
2) Go to the Flight Alerts widget > View
Tap on the subscriber
Select Delete
Android
Turn off alerts for the subscriber
Go to Flight Alerts widget > tap on Configure or "X More".
Select Settings bookmark
Turn off Alerts
How to Delete the subscriber
In the Settings bookmark tap and hold the subscriber
Select Delete