Once you've logged into the account

1. Click on No Thanks

2. Click the Registered Domains link.

3. Click General Settings.

4. Finally, click the Email Auth Info to Registrant link.

This should send the details you need directly to the email address that your PhotoMerchant account was registered under.
Of course, please let us know if you have any trouble receiving the details from eNom

(..and don't forget to check your Spam / Junk folder!)

- Done! -