how to remove network provider sim lock?

Click on the link to read Apple's support article on how to unlock your iPhone for use with a different carrier. - How to unlock your iPhone for use with a different carrier - Apple Support - Only some carriers offer the ability to unlock iPhone for use on any carrier. Follow the instructions in this article to unlock your iPhone.

Click on this link for iPhone: Wireless carrier support and features in the USA and Canada - Wireless carrier support and features for iPhone in the United States and Canada - Apple Support - including a list of which ones offer unlocking.