How can I prevent user from disabling the Mcafee VirusScan Enterprise 8.8? Is there any Registry or Local Group Policy that I could do it?
Whose owns the machine in question?
Is it the User's or the Company's?
If it's the former, then there's pretty much nothing you can do about it. It's their machine and they can do whatever stupid things they want to it.
However, if it's a Company machine (or if it's connected to the Company's internal network) then things are very different.
Your company should have Policies in place that restrict what Users can and can't do to "their" computers. Disabling provided anti-virus software should definitely be on the Naughty List.
Furthermore, why do your Users even have permission to do this in the first place?
It has been commonplace since Windows Vista to have Users operate as "Regular" users and require "elevated" permissions to pass through the User Account Control (UAC) "challenge" before they can do anything "nasty" to "their" machine - and most Users are not given that permission!
No "elevated" permission on the machine? No disabling the anti-virus.
Policies are the answer here, whether they are implemented technically, via Windows "Group Policies" or procedurally through a [written] [contractual] document that Users have to agree to before they use "their" computer.
If you want the Macafee to run all the time instead of getting stopped by other others. You can try the below things.
You can run the Antivirus with elevated permission using UAC Prompt Check here for to run the software with elevated privileges using UAC Prompt
You can run security policy using the run command
secpol.mscCheck here to run the security policy