If you would like to change the email address associated with your account, you can do so on your Airtable account page. To get to your account page, 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 Account option (which has a little silhouette of a head next to it).
This will bring you to the overview section of your account page. You can also go directly to https://airtable.com/account.
To change the email address associated with your Airtable account, click the Edit email option next to where your email is listed.
To update your email address, you'll need to enter your current password and the new email address.
If you signed up for Airtable with a Google login, you will not be able to edit the email associated with your account unless you add an Airtable-specific password to your email (separate from the password associated with your Google login). Clicking the Edit email option will instead bring up a prompt for you to add an Airtable password.
Clicking the add an Airtable password option will send a password creation link to your Gmail inbox