Antivirus Remover is a free tool which provides easy access to 30+ antivirus uninstallers and cleanup tools. These may be very useful if you need to cleanly remove every trace of a security application, perhaps because you're having problems installing a later version.
Launch the program and it displays a list of supported uninstallers. On our test system this included products from Agnitum, Avast, AVG, Avira, Bitdefender, BullGuard, Dr Wen, Emsisoft, eScan, ESET, F-Secure, G-Data, IOBit, K7, Kaspersky, Malwarebytes, McAfee, Microsoft, Norman, Norton, Panda, Quick Heal, SUPERAntiSpyware, Trend Micro, TrustPort, Webroot, WinPatrol and ZoneAlarm.
By default this list shows only products compatible with your system (64-bit uninstallers won't be listed on 32-bit Windows). If you'd like to download a tool for use elsewhere, right-clicking the list and selecting "Show full list" will display everything.
This kind of cleanup tool generally works best when run from Safe Mode (with networking). If you're just running Windows normally, Antivirus Remover warns you of this and offers a "restart into Safe Mode" option.
Otherwise, downloading any uninstaller is as easy as double-clicking it and choosing a location (there are one-click options for "temporary directory" and "desktop"). Antivirus Remover then downloads the file for you and, on completion, offers to launch it.