How to unlock a iphone when l don't know the users name or password?

How to unlock a iphone when l don't know the users name or password? - 1

You don't that's the point of user names and passwords!

You don't. That phone is stolen, and you can get into legal trouble for that.

You don't & that's by design

Consult your nearest Apple Store and if you need to guard your device, you can use Leo Privacy Guard and hide your personal images and videos and it also lock applications, which will be an extra security feature.