The drivers/control panel/physx can be removed in the control panel(select add/remove programs or programs and features depending on your OS.) Use that. If you want to be extra safe run Driver Sweeper in safe mode afterwards;http://www.guru3d.com/category/driversweeper/
After deleting the drivers your card will use the default vga drivers that come with Windows.
Then install the latest drivers Psycho linked you to.
Afterward you can disable any of nvidias background programs and services through msconfig and services.msc(type them in the run box from the start menu.)
I know for a single card it should operate fine with everything disabled but you are saying you have an SLI set up. I'm not certain if both cards will be functional if you get rid of everything. Perhaps someone else knows?