Track exists after turning off navigation on exit dialog.
Here you have action path:
1. turn on navigation, set start and stop from the map, and start e.g. by car
2. tap 'back'
3. there is dialog to minimize or stop navigation and quit
4. tap small stop navigation square in active processes (right below dialog title caption)
5. shows dialog to cancel or exit
6. tap cancel
now navigation is off but on the map there is still track from navigation.
i found that i can delete that starting new navigation and closing it in normal way or i have to tap on that track and from track menu choose to delete, there is no other way to delete that relic trace.
i think that described stopping of navigation should work the same as normal navigation stopping.