There is a special procedure to uninstall add-ons from Internet Explorer. Use the guide below to see how to remove the application:
Internet Explorer: open Tools → Manage Add-ons. Select the intended add-on press Disable.
Secondly, try using Revo Uninstaller. Even if it can't uninstall the application normally, it will force it to uninstall by wiping out all traces of its presence from the system.