apple id

You will need their assistance. There is no known way to bypass activation lock without the assistance of the previous owner. See: Activation Lock for iPhone, iPad, and iPod touch - Apple Support

If you know their Apple ID and password so you can sign them out.  You need to be able 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. Apple won't unlock it.

Turn off Activation Lock - Apple Support.