I received a replacement phone from apple store and need the new phone unlocked how do I unlock the phone

What do you mean by "unlock"? There's 3 kinds of device locking.

1) Carrier lock: How to unlock your iPhone for use with a different carrier - http://support.apple.com/HT201328 - Only some carriers offer the ability to unlock iPhone for use on any carrier. Follow the instructions in this article to unlock your iPhone.

2) iCloud: Activation Lock - http://support.apple.com/kb/PH13695 - This is a security feature so only legitimate (i.e., not stolen) redistribution of devices is possible. See: Turn off Find My iPhone Activation Lock - https://support.apple.com/HT201441 - If an activation lock was put on a device, only the owner of the account that applied the lock can remove it. Get them to remove it or return the item for a refund.

3) Device lock: If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled - https://support.apple.com/HT204306

Locked how?

If its locked to a carrier only the carrier it is locked to can unlock it as explained in the support document you came from.

The replacement iPhone should be exactly the same as the one you submitted for repair including its lock status. If the previous one was locked to a carrier, the replacement phone would be locked to the same carrier the other one was.

If the other one was not locked because it was officially unlocked by the carrier, or was purchased unlocked from Apple directly, then the replacement iPhone would be unlocked.

Contact the carrier.