There was a time when McAffee Antivirus was the king. It was also shareware. It was also the DOS era. At the same time Peter Norton released the Norton Utilities and became a millionaire. Thousands of people had their life's work saved with the Norton Utilities Unformat right after discovering that the DOS command FORMAT formatted the C:\ drive not the A:\ drive unless you told it otherwise.
In the late 1990's AVG burst on the market. It was free for life for schools and worked well. I promptly ordered twice as many free licenses as U. City had computers.
That was then. This is now.
Most new computers come with McAffee or Norton antivirus. Every Adobe update asks you if you want to install one or the other. AVG still has a free version. They all slow down your computer as much or more than the viruses they are supposed to prevent. I say supposed because McAffee and Norton haven't scored better than middle of the pack in an antivirus test in years.
Just remove them.
The good news. Revo Uninstaller will remove Norton and McAffee very easily. The Norton AV takes longer to remove, but in the end it is removed.
If you have Windows 7 or newer, AVG might be able to be removed with the Programs button on the Control Panel. Why did Add and Remove Programs get moved to Programs? I don't know. For someone at Microsoft it made perfect sense.
AVG is another story. In addition to the AV product, AVG has a toolbar for your browser. It is supposed to check websites and provide safe search results. What is does is report every search you make and sloooowww down your browser. Revo will not remove it (or didn't the last time I tried.) Microsoft Add and Remove programs may or may not remove it. Nicely AVG does have an AVG 2014 removal tool. http://www.avg.com/ww-en/utilities What a pain from what was a really great company. There are different uninstallers for different Operating Systems. Make sure to use the version for your OS.
Gotcha! Some manufactures sell 64 bit computers with 32 bit versions of the OS.
“So, you don't like those antivirus tools, what do you use?”
I use Microsoft Defender and the Malicious Software Removal Tool. Free, easy to use, prevents most things and doesn't cripple the compute while doing it.