try this; http://androiding.how/bypass-frp-lock-google-account-verification-nexus-6p-5x-android-devices/

I see you need the old owners email, but this has steps to bypass the lock.

 

I have a stylo2 I bought and can't get passed the Google account lock. Can u help

 

The post above your has a link to an article with advice on how to bypass it (which has other such links within it), but since any such trick is a security hole Google will work to close them off. So try the things it suggests, but I can't guarantee that they will work for you.

So the best would be to speak to the person you bought it from. The whole point of an anti-theft system is that it has to be hard to bypass. The previous owner should have removed the account from the phone before resetting it, but since they clearly didn't, logging in with that account (which can then be removed and replaced with your own) is by far the simplest, and possibly the only, solution.

If you bought it second-hand from a shop rather than an individual, return it for a refund on the grounds that it's not useable. Consumer protection law should be on your side there.