Disable Two-Factor Authentication on refurbished iPhone 6

I had to replace my iPhone 6 with another iPhone 6. In order to transfer my info from the first phone to the replacement, I was required to choose a passcode to open the new phone. (I had set it up to NOT use a code.) How can I turn it OFF again? I have been trying to finish setting up my phone and have been stuck on this for 2 hours. I gather that I could do it by resetting my password, but I don't want to do that. I have tried to do this on my iMac and my new iPhone. When I go into Account Details to where a box should pop up asking if I want to turn it off, there is no box popping up. I truly HATE having to use the numerical passcode. Can anyone help? Please?