gps-speedsurfing

Hope someone can answer this, i turned off my GW-60 watch at end of my session and put the watch watch my clothes box however with all my windsurfing stuff in there my watch turned itself back on and recorded the speed back home,  when I tried to upload the data to GPS windsurfing.com it downloaded all the data in so speeds are incorrect,  can I remove part of that data for the trip on the way home so leaving me with the correct windsurfing data

ITALIANSURFSHOP