Here’s how you can change the email address you use as your Things Cloud username.
Switch to another email address
There is no way to automatically switch your account from one email address (username) to another. We recommend that you delete your existing account and then create a new one with a different address.
When you delete your Things Cloud account, only the data in Things Cloud is deleted. The data which is stored locally on your devices (which you see inside of Things) is not affected.
If you no longer have access to your original email address
If you no longer have access to the email address and password that you used originally to create your Things Cloud account, you might not be able to delete your account. In such cases, please simply create a new Things Cloud account. Start by going to Things > Settings > Things Cloud and turning Things Cloud off. Then turn it back on and follow the instructions for creating a new account.
Once the new account is created, Things will automatically upload your to-dos into it. Then just sign into this new account from your other devices, and you’re good to go.