More likely the "End of life" message is referring to OBi100 and OBi110 devices. Even if you don't have one of those. And that message does NOT mean that the device has or is about to be rendered non-working. It means no more firmware updates will be released and OBihai tech support will not help to resolve any problems.
Resetting an OBi does not of itself remove it from your dashboard at
obitalk.com so there should be no need to do the **5 nnnn process.
If your OBi is still registered to the dashboard of your original account you will NOT be able to add it to the new account you have created.