WINDOWS XP: Choose Start Control Panel Add or Remove Programs, then mark the game you want to uninstall and click the "Remove" button.
WINDOWS VISTA / 7: Choose Start Control Panel Programs and Features, then mark the game you want to uninstall and click the "Uninstall" button.
WINDOWS 8 AND 10: Press the Windows Key + x, choose Control Panel Programs and Features, then mark the game you want to uninstall and click the"Uninstall/Change" button.