To do this, first click Site and then Customize Design. In the section bar, click the Design Settings button.
In the template settings, select Off for the SmugMug Header and Mini for the SmugMug Footer options to hide and minimize them. Click Save.
While you can hide most of the footer, the Powered by SmugMug and log-in links cannot be removed.
Note: As a logged-in site owner, you'll always see the SmugMug header in your navigation bar so you can work on your site.