You can do this by logging into your Online Account Manager at:
http://www.hostingcheck.com/billing/
Then, Click "Domains" from the Menu,
Then, Click "My Domains" from the Drop Down Menu,
Then, Click on the "Manage" Button next to the Domain Name that you want to Manage.
Then, Click on the "Registrar Lock" Tab, and Click on the "Disable Registrar Lock" Button.
That's it! It should now show the "Registrar Lock Status" as "Disabled"