how can i uninstall ads by MacPriceBuilder

If you are running a MacBook Pro or Yosemite, you don't have Classic, the forum you posted in. Once you visit a website, a prevailing document known as a cookie is often stored to say you visited the website. You can edit your browser preference to remove cookies from said sites, so their advertisements don't appear as frequently on different sites. Some advertisements though are normally the part of certain websites, and you can't remove them from that website.