Locked out of iphone and do not have previous owners info.

I purchased an iphone from a friend who purchased from someone else. They never got any of their info and theres no way to get it. When trying to log into the phone it asks for apple ID and password. The phone was never reset, and now I can't get back into it. Not sure how to get back in! Oh yeah, I got locked out when updating the phone to IOS8