If you would like to change the email address associated with your account, you can do so on your Airtable account page. To access your account information, click the circular face icon in the top right of the home screen. This will bring up a dropdown menu with several options; select the option "Account" (which has a little silhouette of head next to it).
This will bring you to the "Your Account" page. Click the little blue pencil icon next to your email address.
This will prompt you to enter your current password, and the new email address you wish to use. When you're set, click the "Save email" button.