If you are talking about the footer in the ShopSite backoffice, then it depends on what kind of access you have to the website. If you have access to the ShopSite cgi directory (usually named 'ss') then you can customize some elements of the footer by editing the global.aa file that is there according to the instructions in the documentation at:
http://www.shopsite.com/help/10.1/en-US/install/customize.html
Make a backup copy of the global.aa file first, though, because it is an important file and if you screw it up you could break the whole store.
-Loren