My iPhone4s iOS 9.1 beta

Okay. Serious question. I bought an iPhone 4s off my friend, and it was not formatted. The iCloud was under his dads iCloud, and his dad had Find My iPhone activated. Since i don't know my friends dads password to his iCloud, i can't turn find my iPhone off. I've looked everything up on youtube, and i've seen people do tutorials of a iOS 7 (Or iOS 8) glitch on turning find my iPhone off without the iCloud password. Problem for me, is i updated my iPhone to iOS 9.1, and this is no longer possible. I then looked up tutorials on how to de-install iOS 9 to iOS 8, but since i had Find My iPhone ON, i couldnt do this. Please tell me the iOS 9.1 way of turning Find My iPhone off on an iPhone 4s. Thank you. BTW i can just ask my friends dad but he forgot and he can go on his email to verify and set new password but he hasn't responded to my fb messages and i don't know when he will.

If your dad's friend has no way of resetting his password, then you're out of luck. There's absolutely no way to ever bypass it.

Tell your friend to tell his dad to reset the password and to log into his iCloud account on a computer and remove the iPhone 4S from his account.

By the way, you wouldn't even be able to go back to iOS 8 anymore.

My iPhone 4s has decided to not deliver text messages I've been through txt support to no availle what can I do