I got second hand ipad and it is still linked to another Apple ID.
Is there a way to erase if you don't know the person who's id is still linked?
iPad (5th gen) Wi-Fi
You will need to contact the person that previously owned it for them to remove the Activation Lock. If you cannot contact them, try to return it for a refund. The device is useless to you unless the other person removes the lock. There is nothing you can do to try and bypass Activation Lock.