It is important to only have one antivirus program installed on a computer. Having more than one may seriously slow down the computer or cause Windows to become unstable, freeze or even refuse to start up at all.
Therefore you should always uninstall any existing antivirus program before you install another one. The usual method of uninstalling via Add/Remove Programs (XP) or Programs And Features (Vista and Windows 7/8) should work in most cases.
LAST UPDATED – FEBRUARY 2014
However, sometimes the uninstallation process itself fails and you can’t uninstall the antivirus program completely. Most antivirus companies produce a special uninstaller program (removal tool) to forcibly remove their software – even if it no longer works or does not appear in the list of installed programs.
The following is an up to date list of common antivirus removal and uninstall programs – in most cases you just need to download the removal tool, run it and follow the instructions to completely remove the antivirus program.
List Of Antivirus Uninstall Programs / Removal Tools
Read the info page for any special instructions. If an uninstaller fails, it may need to be run from within Safe Mode.
avast! 6 – Info – Download – Note: must be run within Safe Mode
avast! 7 – Info - Download – Note: must be run within Safe Mode
avast! 8 – Info - Download – Note: must be run within Safe Mode
avast! 2014 (Avast 9) - Info – Download – Note: must be run within Safe Mode
CA (Computer Associates) – CA no longer support these antivirus products as they were sold to Total Defense – a company which does not appear to provide a tool – try using the free Appremover program to uninstall.
NOD32 – Use the ESET uninstaller (see ESET above)
Symantec - Use the Norton uninstaller (see Norton above)
Total Defense - See Computer Associates (CA) above
If you have an antivirus program that is not covered above (or find a broken link) let me know in the comments and I will try to update.