I did this many months ago, so I do not remember exactly how I proceeded, but I have vast knowledge about Windows and probably waded through registry entries and checked services and processes. Perhaps I even looked for driver files on the hard disk based on their date. Something along that line.
Bottom line is that you cannot do it unless you really know what you are doing in Windows. The complexity of this is probably why Intel refrained from writing a proper uninstallation routine for this. The danger of rendering the Windows installation unusable was too high from their standpoint, so they resorted to leave the drivers in place.
Again, I am writing all this based on my memories from half a year ago, so not everything needs to be...