Unfortunately, you can't change an agent's email because this address is used as an identifier.
However, you can achieve a similar effect by adding a new agent, and deleting the existing agent afterwards.
If you are the owner of the account and want to change your email, you can still follow the same steps and let us know of this change so we can mark your new email address as the owner of your account.
For a more specific request regarding this subject, please contact our support team.