Because it may be acting as an "add-on" in your browser, try removing from the browser by opening Internet Explorer, then click on "Tools-Manage add-ons", then click on the "Toolbars and Extensions" listing on the left side.. See if the popup blocker is listed there. If not, try one of the other listings on the left side of the screen to check for the presence of the blocker.. If found, click once on the listing, then choose to "uninstall" it from the screen.

You might also try the Revo Uninstaller in the link below.. (Use the free version.) It may be able to remove any remnants.

Hope this helps.