If an application was installed using Impulse, you will need to likewise uninstall using Impulse. If you have uninstalled Impulse, you can redownload it from here:

http://www.impulsedriven.com/downloads/impulse_setup_full.exe

Simply install and run Impulse, log in with your account, click the "My Games" or "My Software" tab, right-click on the entry for the software that you wish to uninstall, then select "Uninstall". If installed with a standalone installer, then you can uninstall from under the Windows Control Panel as usual (Add/Remove Programs on XP; Programs and Features on Vista/7). If the application fails to uninstall due to error, some applications can be uninstalled with the following tool:

http://sd.stardock.com/mike/apps/odnt_zapper.exe

This app will need to be run as admin in Windows Vista/7.