I have a GEN one iPad we reset it to factory settings the person that owned it previously has changed ID

I have a first generation iPad I reset it to factory settings they have the activation lock on it the person that had it before me has changed his Apple ID the old Apple ID he don’t know the password for it

so we went into his phone and looked for the device and it’s not showing up so he can’t remove it

so how do we remove the activation lock so I can get it to work where I can use the iPad