Carrier settings file

To tell if your phone is truly factory unlocked, put any carriers gsm sim in the phone. The sim does not need to be activated. If you get any error messages, your phone is not unlocked. An unlocked phone will display "no service" if the sim is not activated.

What I'm saying is this, yes you have a carrier authorized unlocked phone. They are available where you live. However, even though your carrier unlocked your phone, that does not necessarily mean that they permit you to edit the APN settings. Some do, some don't. That's why you need to contact the carrier you got the phone from originally. Apple has no control over this. We are prohibited by apple's terms of use from telling you how to do so in this forum.

See hexonxonx post above.

Yes, I understand what you're saying. But, Apple is not a carrier. The phone, to be used as a phone, had to have been activated through a carrier, unlocked or not. And again, just because you have an unlocked phone, that doesn't mean the carrier you originally activated it with permits editing of the APN files. Some do, some don't. If the originally carrier permitted this, you'd be able to do so in your settings.

Quoted from the bottom of the support page you sited:

You cannot change the information in the Cellular Data Network screen unless you have an authorized, unlocked iPhone or your carrier allows editing the APN settings.

I'm not trying to be difficult. Fact is, on this forum we are prohibited from telling you how "hack", remove, edit, or anything else regarding your carrier file. I truly believe your phone is a legal unlocked phone. As I see it, you have two choices, 1)Contact Apple where you bought the phone, 2)Contact the carrier who's settings you want to remove. Even if I were to tell you how to alter the settings, this entire thread would be deleted before you got my response.

Unfortunately, the answer to your question is considered "hacking" the phone. Apple's terms of use prohibit those discussions in these forums.

Your phone could still be unlocked, but your carrier may not permit editing of the APN settings. I think you need to contact your carrier.

You can search Google for ways to modify the carrier file. There are even websites that will upload one straight to your phone. It's very easy to do.

I mentioned before, Google is your friend. Seriously. No need for the Apple store or anywhere else in this matter.