AntiVirus Removal Tools
Here is a list of for leading antivirus and security software for Windows.
Avast : Use their uninstallation utility aswClear.
AVG : AVG Uninstaller.
Avira : Avira AntiVir Registry Cleaner Tool will help you clean up all the registry entries left by this anti-virus software after the uninstallation.
BitDefender : Uninstall BitDefender | 32-bit | 64-bit.
CA Internet Security : Knowledge document and uninstaller.