Have you checked Add/Remove Programs in Control Panel to see if there is an
entry in the list for your antivirus software? If it's listed, use
Add/Remove Programs to uninstall. Also, check its shortcut on the Start
menu, it may have an uninstall shortcut. If you find nothing in either
area, go to the application maker's website and look for instructions on how
to uninstall the application or contact their tech support.