How to correctly uninstall a preintalled antivirus program

Background: Laptop with Windows 8 preinstalled. Removed preinstalled McAfee trial version (never officially activated it but it works out of the box) using MCPR.exe. Updated to Win 8.1 and used Windows Defender with no issues.

At some point I attempted a System Restore and got error 0x80070005 which says it could not complete due to a problem with an antivirus program (or something like that, I'm sure you are aware of the error). I have to assume it was somehow related to McAfee as no other AV had been installed, other than Defender. Long story short nothing I did would get System Restore to work so I reset the computer.

Heres where I am now. After the reset I left McAfee as it is. Again did not officially activate it but it is functioning. I did all the Windows 8 Updates and did a test of System Restore and it works fine. I have now updated to Windows 8.1 and would like to uninstall McAfee. But I fear somehow when it was removed the first time something went wrong which is why I was getting the error when trying to use System Restore. I don't want a repeat and would really like to have System Restore available.

So what should I do to remove McAfee so it will not interfere with System Restore? Uninstall first via add/remove programs and then run MCPR.exe? I did not do that last time. Just run MCPR.exe and reboot? That's what I did last time and then System Restore did not work due to an anti virus related conflict.

May be best to uninstall with "Revo Uninstaller" and let it clean leftovers. Before uninstalling, first disable it from auto start and it's service.
Another way (I'm not sure how effective it is ) McAfee Consumer Products Removal tool Download
Some of those AVs are really stubborn to uninstall. Just for safety, clean up any leftovers and and registry.

CountMike makes a valid point, most AV's are hard to remove since they do embed themselves deeply into a system. McAfee is one of the more PIA ones to remove. After removing it via uninstaller from several systems, I've seen problems pop up weeks later due to leftover files.

In addition to running Revo & The McAfee uninstaller, d/l CCleaner (the free version will work fine), after uninstall of the AV, run it & allow it to clean out the extra files & leftover registry keys if any. As in any case when removing reg keys, be sure to make a backup of your files. CCleaner will give you the option to save the deleted reg keys, so that you can reinstall them just in case.

When using Revo, please read the documentation well, as it is easy to hose your OS. Remove only the bolded reg keys.

Another alternative would be to d/l an ISO image of Windows, & do a clean install. As long as you have a valid windows key, you should be able to re-install Windows from scratch & bypass the crapware installed by default by the PC maker.

http://www.eightforums.com/tutorials/18309-windows-8-windows-8-1-iso-download-create.html

Just to ad something, improperly installed or uninstalled AVs are specially hard to remove when that is botched, so you got to make sure it's all gone first time.