Topsites.me is a browser app, which means it can be deleted just like any other app.
For Google Chrome - Open page chrome://extensions/. Find New Tab Page app and click on the trash button.
For Mozilla Firefox - Open menu Tools - Extensions. Find Topsites.me app and click on the Delete button.
For Internet Explorer - Open Control Panel and from there, launch Programs and Features. Then find Topsites on the list and double-click it to launch the uninstaller.