Cannot Erase content from iPhone 5s (and i feel like i've tried everything)

I recently upgraded to a new 6+ and those at Verizon never bothered to mention that once the new phone is activated and the old phone is deactivated you won't be able clear the phone because there is no longer an internet connection or ability to connect via wifi.

in short, this is what i've tried:

1. erase all content and settings on phone. cannot because cannot login to apple id without internet connection.

2. tried to erase using itunes. cannot erase until turning the 'find my phone' feature off, which cannot be done on the phone without the internet connection.

3. tried to erase phone from apple id account via website. won't work, because the phone will not technically 'erase' until it is connected to the internet...

this is beyond annoying and frustrating. i'm so close to just sending the phone into verizon as-is and let them monkey with it, but i'd rather not take that chance...