You can uninstall the game with the Combat Arms uninstaller from the installation folder. Also you can use Add or Remove Programs feature:
If you use Windows XP or bellow you can go to Start > Control Panel > Add or Remove Programs. In the Currently installed programs box, click on the Combat Arms 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 Combat Arms and click on Uninstall.