How to unlock the icloud
How to bypass the owner apple id
Unfortunately, you cannot do very much with your phone unless you get assistance from the previous owner, they should either provide you with the password to unlock it or remove their account from the phone entirely remotely through iCloud.com > Find My Phone.
If you aren't able to get assistance from the owner and are unable to get a refund for your purchase, please dispose of the device responsibly by sending it for recycling.