Reprogramming a USED Ooma device. No way to access Voicemail

I bought a used Ooma device on eBay. The former user no longer has an Ooma account. When I call my Ooma phone #, I get the voicemail of the guy who owned the phone, including his recorded message with his totally different Ooma phone#. Since he has no Ooma account, I can’t ask him to go online and fix it. There should be a way that a new user can delete the info of a former user.

With the phone attached to your telo dial your own number, got into settings, and record a new greeting.