Unless you want to take it apart and disconnect it.
Just disable it System Device Manager.
This is the problem, Disabling the touch pad is not an option, you can only to an Unistall and when you Uninstall it just re-installs the next time you go into Windows. Don't want to open it up because it would probably void the warranty. Just as important, it's my wife's machine and if I open it and screw anything up, I'm dead meat.