How do I disable emergency calling entirely from my child’s iPhone? He has called numerous times.

Hi dnamkung,

Welcome to Apple Support Communities. Emergency calling is a great feature, and we can see how it will help people in a time of need. However, we do understand some wish to disable that feature. We're happy to assist.

Go to Settings > Emergency SOS. From there, you can enable or disable the feature:

Make emergency calls on iPhone - Apple Support

Cheers!

Hello Dnamkung,

There is no way to currently disable SOS slider from the power screen of the iPhone. We'd suggest providing any feedback you have about this here: Product Feedback - Apple

Wishing you well, take care.

Note that the solution given above will not prevent your child from manually dialing an emergency number (e.g. 911).

No, you can't completely disable that feature.