Have bought IPOD touch 9.1 for son for Xmas. Tried to back it up from old IPOD 6 which had an old appleid on it. Now can't get new IPOD to change the appleid to my current id

I have bought an IPOD touch 9.1 for Xmas. I tried to back it up from old IPOD touch 6, but this has an old apple id on it, which unfortunately has transferred to the new IPOD. We don't have access to the email address linked to that appleid. I have tried to reset the new IPOD, but it keeps coming up with needing the old appleid password.

Does anyone know how I can get this new IPOD to either reset to the new appleid, or to erase it to get rid of the old appleid?

It is on icloud where the old appleid is present, everywhere else the current appleid is listed.