At the top of your iPhone, how do you turn off where it displays your phone company?

I just got my iPhone, and at the top of my screen it says AT&T and then it shows how many bars of reception I have. I noticed many people have no phone company at the top, how do I change the settings so it doesn't show my phone company, please help

You can't.

This is officially not supported by iOS. I wouldn't modify if you don't know how to as it carries risk