You can access "Private drive" app by navigating to http://tracksw.com/trackpriv/. In login screen, enter device ID of your vehicle and password.
When private drive is activated, vehicle's current location will not be seen in TrackSW software's current devices tab or history. However, the distance travelled will still be calculated and can be seen in the report.
When private drive is off, the tracker and software will operate as usual.