You can change the email address that is set up with your developer account by logging into the my.MYOB website here are the steps below:
1. Select the developer account on the top right-hand side of MY.MYOB
2. My Account
3. Change Login, From here there will be an option to change your email address.
Changing the email address will stop any integrations that have used the previous email address. This means you will need to log into secure.myob.com and revoke access for any integrations that have used the previous email address and then you can complete OAuth again with the new email address.
Please note: this will only allow you to change the email address if the new email has not been used before and does not have a current My.MYOB login. If you have any questions, feel free to log a ticket with the Customization & Integration Team.