Uninstall old version of SEO pack

I installed your "all in one seo pack" plug-in originally when we launched our WP3 site. It was put in the must use folder (I assume these were the instructions at the time, as our developer installed it that way). Now, I can't seem to figure out how to uninstall is from the site to upgrade and/or install the new SEO plugin that you guys put together. Any ideas?