Do you have a guide as to how to use the map builder? Specifically how to "undo"
The map line for the trip builder is fully draggable so if you make an error the points can be simply repositioned in the desired place.
Once saved if the trip is then found to be incorrect, it can simply be deleted. This is done by viewing the saved trip while logged in as the owner.
If an error is made before the trip is saved one can simply start over.
I hope this information helps