forcibly remove McAfee

Sometimes you need to forcibly uninstall McAfee.  Go to the program directory, Common Files and issue:

Frminst.exe /forceuninstall

Sometimes the forceuninstall fails.  And you see all an error having to do with MFEagent.msi. This may be due to a corrupt MSI installer.  You'll need to remove references to the MSI by doing thus:
Open regedit, HKLM  software > classes > Installer> Products > and find the folder that references the "McAfee Agent" and delete that whole folder.
Then re-install the agent as normal. In effect, what we're is doing is telling Windows Installer that the McAfee Agent is no longer installed and we're overwriting all McAfee Agent files.