This may not apply to you but it seems that by default Windows 8.1 comes with McAfee Antivirus. After using the trial period and you don't want to keep the McAfee Antivirus on your system then you should uninstall using Programs & Settings > Remove or alter a program.
After uninstaling the McAfee Antivirus, there will be 3 persistent executables that cannot be delete from the system. Attempting to close this executable with task manager or Process Explorer will not work.
The persistent executables are:
mfemms.exe
mfevtps.exe
mfefire.exe
The solution is create a registry key to block them from auto starting with the system and delete them manually. This can be done automatically with the little batch available below.
Download & Run the batch file available below with administrative privileges.
How to:
1) Run the Batch and the first time it run it will create the registry keys.
2) Reboot the computer (To stop the persistent executables)
3) Run the Batch again to remove the files from the system.
4) That's all