How to change email address tied to default identity domain

Summary:

Trying to change email address tied to default identity domain on free account and unable to do so

Content (required):

Cannot figure out how to change email address tied to default identity domain on free account. Also unable to destroy account and start from scratch. This is delaying work to build and test a new application.

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):