There are so many antivirus and other malware software applications out there it is near to impossible to keep up with them all. Many if not all have removal tools to use in case their normal uninstall process fails.
Here are a couple of links with some instructions to get started on uninstalling your antivirus.
Comprehensive List of Uninstallers or Removal Tools for Antivirus Software
both links are getting a little aged, so take a look. If you have trouble getting specific uninstalls to function, let me know and I will try to do a write up specifically for it.
As you may have seen several times many antivirus packages out there love to install, but hate to uninstall themselves. There are some very big ones other there that almost always fail to uninstall completely. Many of them have created their own little uninstall utility program to finish the job. But you have to wonder, if their software uninstall option did not work, how can I trust their uninstall utility to succeed?
Here is the solution. One app to kill them all. AppRemover by OPSWAT is an utility that will remove all of your most common (and some not so command) antivirus, antispyware, and several other security packages. Download it at AppRemover, it is free for personal and non-commercial use.
AppRemover is a well formed utility. It does not require an installer (which is great). Running the remover simply asks if you want to uninstall a security package or clean up a failed uninstall. You select what you would like to do and let it scan. After it finishes the scan, click next and select what you would like to remove.
At well over 100+ applications that it can removed, I will not attempt to list them all. But here are a few that I have seen that could be very useful: Avast, AVG, Avira, CA, Eset, F-Secure, GData, Kaspersky, Lavasoft, McAfee, MSE, Norton, Panda, PC Tools, Trend Micro, and 100+ more.