You can change the email address that you use to log in by going to the Users page in Settings. Note that the email address you use to log in is not necessarily the same as your contact email address in Halaxy - you can set different contact email addresses in your Email Sender Preferences.
To change the email address you use to log in:
Log in using your current email address.
Click Settings > Users.
Click the Edit (pencil) icon to the right of your name and details.
The Edit User pop-up will appear. You can change the email address by updating the current email address and confirming the new email address:
RESULT: The email address you use to log in will now be updated. To log in, you must use the updated email address.