Go to account.mylio.com and log in.
Click "Change Email" below your email address.
Enter and confirm your new email, then select "Change Email."
Next time you open Mylio Photos, log in with your new email.
If you cannot update your email address, the email address may already be associated with an active Mylio account. If you believe you are the owner of this email address, please log into the associated account and delete the account. Once this is done, the email address will be available for use.
If, for whatever reason, you are still unable to change your email, contact support.