This is one of my "I am sure there is an easier way" but I restart "navigate to" and select home. I then cancel it before it finishes. The unit just tells me where I am. Does that help? Maybe someone has a simpler solution.
First go to Perferences page 3 of 3 and select "Show All Menu Options". Select Continue.
Then on Main Menu page 3 of 3, you'll see "Clear Route" on the top third option. This is what you need to do to cancel or clear a route planned.