If you use Windows XP or below you can go to Start > Control Panel > Add or Remove Programs. In the Currently installed programs box, click on the Camera Assistant program and then click Remove.
If you have Windows Vista or above you need to go to Start > Control Panel > Programs > Programs and Features. Select the Camera Assistant application and click on Uninstall.
After that, run a registry cleaner to make sure that there are no leftover rogue registry keys in your system, navigate to the official web page, identify your computer model and download and install the latest webcam files available.