From Test-Scratch-Wiki
Login to your Scratch account, and click on your username in the top right corner. A drop down menu will come up. Click the "account settings" button. On the left of the page, you will see three tabs. "Account", "Password" and "Email". Click the "Email" tab. Find the "Type new email" box, and enter the email address you want to change to. Click the "Change email" button, and you're done!
