One of our group got a room about 45 minutes away.  He’s hoping that something closer opens up before housing locks down.  Having never done this, I thought someone here might be so knowledgeable and kind enough to help.  

what’s the best way to do so?

See the FAQ for changing hotel reservations

Regrettably, the modify and cancel faq only has instructions on how to cancel.  

From the housing webpage:

To modify or cancel your room assignment, log into your Gen Con account, visit your My Housing page, and click the “Manage Room” link for the assigned room you'd like to change. The link will connect you with the online system where you can make the desired adjustments. Changes will not go into effect unless you click the “submit” button to confirm the change; closing your browser before submitting the change will leave the original assignment intact.

Ah, I see where I went astray.  Thank you both for your help