Off wireless

You can't directly.

Here is the procedure to follow:

If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support

Apple cannot do that because Apple does not provide cellular / wireless service to your iPhone. Contact your Cellular Service provider (Your phone company) and have them turn the service OFF to that stolen iPhone.

Also review the information in the web link that Dogcow-Moof provided in the previous response.

Axel F.