How do I turn off SOS on my iPhone?

If “SOS” is showing in the status bar, it isn’t a setting you can turn off. It means the iPhone isn’t connected to your carrier, but emergency calls may still work.

Try turning Airplane Mode on for about 15 seconds, then turn it off and restart the iPhone. If SOS remains, check that your cellular line is turned on under Settings > Cellular, then contact your carrier.

Apple has more steps here: If you see SOS, No Service, or Searching on your iPhone or iPad - Apple Support

If you’re stuck on the Emergency SOS screen instead, restart the iPhone.

SravanKrA wrote:

The pic below is self-explanatory: to turn off emergency SOS

That picture tells you how to stop sharing your location with first responders if you make an emergency, life-or-death, 911-type call.

I don't think that is what the OP is asking about or what the OP wants to do. Most people who have to call for an ambulance (heart attack, stroke, etc.), the fire department (their house is burning down), or the police (someone has gone on an "active shooter" spree in the mall) want first responders to know where they are!

The OP appears to be under the common misconception that "SOS" is something that you can simply "shut off", to get full cellular phone service. It isn't. It typically means that you don't have a connection to your carrier's cell phone network (you're in a "dead zone") or there is a problem with your account with them. The SOS means you still can make emergency "life or death" 911 type calls because other carriers are required to accept those even if you are not their customer. To troubleshoot your cellular service, you need to contact your carrier.

Clicking that "Stop sharing emergency location" button will do nothing to restore the OP's cellular service – but might well cost first responders critical time if the OP suffers from a medical emergency or comes under violent criminal attack.

For No Cellular Service SOS

If you see No Service or Searching in the status bar on your iPhone or iPad (Wi-Fi + Cellular), your device isn't connected to a cellular network. If you see SOS or "SOS only" in the status bar, your device can still make emergency calls.

If you see No Service, Searching, or SOS on your iPhone or iPad

The pic below is self-explanatory: to turn off emergency SOS