Sometimes these Antivirus programs or should I say most of the times these programs like Norton Mcafee wont uninstall from the system. They keep annoying you with messages like Mcafee antivirus already installed and you cant install another antivirus programs. The instructions below will guide you with removing Mcafee completely from the system.
You can use McAfee Consumer Product Removal tool (MCPR.exe) to completely remove any kind of Mcafee Software from the system.
Running the McAfee Consumer Product Removal tool (MCPR.exe) removes all 2005, 2006, 2007, 2008, and 2009 versions of McAfee consumer products.
IMPORTANT: If your McAfee products were preinstalled by the manufacturer of your computer, please make sure to activate your McAfee subscription before uninstalling. Reinstalling from a CD or download will only install your McAfee consumer applications, but may not recover your paid subscription term information.

Download Mcafee Removal Tool MCPR and install it on the system.
Once installed, run this tool to uninstall Mcafee from the system.
Image Credits: www.mynetimages.com
You can use McAfee Consumer Product Removal tool (MCPR.exe) to completely remove any kind of Mcafee Software from the system.
Running the McAfee Consumer Product Removal tool (MCPR.exe) removes all 2005, 2006, 2007, 2008, and 2009 versions of McAfee consumer products.
IMPORTANT: If your McAfee products were preinstalled by the manufacturer of your computer, please make sure to activate your McAfee subscription before uninstalling. Reinstalling from a CD or download will only install your McAfee consumer applications, but may not recover your paid subscription term information.

Download Mcafee Removal Tool MCPR and install it on the system.
Once installed, run this tool to uninstall Mcafee from the system.
If the issue still persists please follow the detailed instructions on Mcafee.
Image Credits: www.mynetimages.com

edited anchor links and line breaks... :D