How to reset iphone 5 with no apple id or password?

I just bought an iphone 5 and went to activate it, and couldnt activate or restore because the 'find my iphone' app is on and I don't have the password to turn it off. I know contact the seller, but I can't. The only info I have is the # and its of the phone I bought. Is there anyway around this?

You need to have them erase it so you can set it up as your own, always check that before buying a used one.