How to stop fire alarm with keypad

I have two First Alert fire and CO alarms connected to my ring security system. I know that I cannot disarm it with my phone or tablet. My problem is sometimes my dad will be home alone and I know he will want to use the keypad to disarm it. He isn't as tech savvy. I can't find directions on how to disarm it using the keypad. I'd love a how to so that I can help my dad. Thanks!