Old apple id

If it is now your phone, you will need to contact the previous owner to have them log out of iCloud or go to https://www.icloud.com/find/ My Phone and erase the device, then remove it from their account. If you can’t do that, the device is useless. 

Turn off Activation Lock - Apple Support.      

You'll never be able to use a new phone that belongs to someone else unless they will give you the needed password.