I bought an Iphone 6 with iCloud and Apple ID not thrown off, how to throw it off?

Question

iPhone

In general, a person bought an IPhone 6, forgot ICloud and couldn’t get out of the apple ID either, I can’t contact a person, and I have a phone with his account. I found on the Internet how to download iCloud via iTunes from a computer. I did everything according to the instructions. A new firmware was installed in it and I was greeted by a welcome screen where you need to select the language, etc. I thought that everything solved the problem, but in my opinion the problem became more serious. When I started setting up the phone, some kind of iPhone activation went on and it came out that I needed to enter the old apple ID, but I don’t know any password or mail,
tell me what to do?

Answer 1

No way. It's called "bought a stolen iPhone"

Answer 2

don't update ios

Answer 3

This video may help you: https://www.youtube.com/watch?v=udPy_Ih5zVU