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My sons brand new Dell Laptop came preinstalled with a trial version of McAfee Antivirus and I proceeded to uninstall it and setup Avira instead which I use because it is free, but I noticed that even after uninstalling McCafee from the Windows 7 Uninstall programs menu, it kept showing up after a reboot as a process and kept popping up a reminder that the trial license was about to expire. It was just coincidence that I found an article on Craving Tech that had a full list of all antivirus software removal tools. It was such a comprehensive list and had direct downloads for you to remove:
Alwil Avast, AVG, Kaspersky, Avira, BitDefender, F Security, Norton/Symantec, McAfee, TrendMicro (PCCillin), Windows Live OneCare, Zone Alarm, ESET (NOD32)
I didn’t want to post the links directly because I want you to visit the original source and download the software removal tools directly from Craving Tech, so if you are looking to remove avast antivirus or any other antivirus software, I encourage you to visit the above article and and download the antivirus software removal tool for your specific product.