You can restore factory defaults using using Settings menu.

1. Highlight Settings and select it
2. Scroll to Restore defaults and select it
3. Pick and choose what you want to restore (check the box) and select OK

Mission accomplished!

Note: You can save waypoints, trails, routes to "my files" . Restore defaults will not erase them.

Manual hard reset will not erase the saved waypoints in "my files" either.