How to turn off Find My IPhone without password and how to delete the account on IPhone 4 or 4s?

So yesterday I found an iPhone in the street and it has an icloud account making it almost impossible to do anything on it and I was wondering if anyone knew how to delete it and turn off Find My IPhone (it is an IPhone 4 or 4s can't really tell )

Are you also going to ask us how to rob a bank, or steal money, or a car? There's a REASON that you can't use a phone with security protection - so WEASELS like you can't use them, making then a *brick.* Turn it into the Police or a phone store - now that we all know what kind of person you are.

Simple answer: you can't.