Q: Unique Find My iPhone / Apple ID Problem

So I buy my wife the new iPhone 6 for her birthday.  We put the old one (4s) in a drawer expecting to sell it.  Fast forward several months: I get deployed to a part of the world that does not have cell coverage for my phone but does have access to good WiFi.  Since we have a MacBook Pro, three iPads, an iPhone 6, an iMac and this extra iPhone 4s, I think "I'll just use iMessage and Face Time to connect with my family back home."  Genius!  She sends me the old 4s and the following problem arrises:

Upon getting new iPhone 6, my wife changes the email / Apple ID to her new email.  The old phone has Find My iPhone with the old Apple ID.  This ID is attached to an email that no longer exists (Time Warner Cable bought out Insight in our area).  We go to recover password on the old ID, it sends temp password email to the non-existent account.  I've try restoring the phone, still says it is necessary to log in and disable Find My iPhone.

HOW AM I SUPPOSE TO USE THIS THING?

Thanks.