I have moved a few times and I don't remember my obihai account or phone number. Can I factory reset it and link it to another google voice number without having to remove it from the account? I would like to reuse the device
Resetting the device does NOT make the portal forget it. Even after resetting, you will not be able to add the OBi to a new account on the portal.
If you really, really cannot get a password reset to work on any email address you might have used to make an account on the portal, it is possible to load an unofficial "alternative" firmware which can configure GV without using the portal.
Or you can connect to GV using the Simonics GV gateway. You can configure an Obi (with standard firmware) for that without using the portal.