Manually uninstall McAfee on Windows systems by using the Uninstall a Program feature or the McAfee Cleanup Tool. On Mac OS X systems, run the uninstaller from the Terminal application. The cleanup tool is free to download.
If using Windows, right click on the Start button on the bottom left, and choose Control Panel from the list. Click Uninstall a Program under Programs, select the McAfee application from the list, and click Uninstall/Change. Follow the steps in the uninstallation wizard, and restart your computer once it's done.
Alternatively, you can use the McAfee Cleanup Tool. Download it from McAfee.com, and run the application. Click Next twice, enter the Captcha, and click Next again. The tool then removes the application. McAfee warns that you must not download the tool for future use as it is updated regularly.
During either process, Windows may ask for your password to grant you administrative privileges. If it does, enter your password.
If using a Mac OS X computer, log in with an administrator account, launch Finder, click Applications, and navigate to Utitilies. Launch the Terminal and type "sudo /usr/local/McAfee/uninstall EPM," and press Return. Enter your account password, and press Return again. Once the Terminal notifies you that it has removed McAfee Protection, type "sudo /Library/McAfee/cma/uninstall.sh," and press Return. Restart your Mac to complete the removal.