I ended up with 2 email accounts on my Nest thermostat, my old work address I can no longer access and my personal Gmail. The thermostat is connected only to my old email. I cannot add it to my current email. Can I merge the 2 email accounts? Or start completely over? I want to adjust my thermostat from my Nest app.
I'm sorry for the late reply. I know it has been a while, but I wanted to ensure that everything is covered here.
Since you no longer have access to your work email address, you cannot use your personal Gmail to add it as a home member to get access to your thermostat. It would be better to link your other Nest Thermostat to your preferred email with your other thermostat so you can control them both remotely.
If you have the Nest Learning Thermostat or the Nest Thermostat E, go to Reset > Account Connection > Reset. This will remove the account permanently, so you can add it to your new account. But if you have the Nest Thermostat 2020 model, a factory reset will bring it back to its default settings.
Please let us know if you need more help.