We just released a new action under the “Account” heading, “Change the login email for another user”.
This is to enable administrative workflows where you need to change the email for a user who isn’t currently logged in and using the app. In general, it’s better to let the user change their own email via the “Update Credentials” action, but this is useful for situations where you are, say, migrating users over from another system and want to update their emails without them taking a manual action.