You can't unless you were the person to submit the route or area in the first place. This is one of those things that I really wish MP would change, but I guess their reasoning is that people who don't want the location of an area known could then go on and put in wrong coordinates or something like that.
I could always leave a comment with the coordinates. But I'll try to contact the "owner" of the area.
I think there is more benefit to allow others to add info and possibly correct info than to protect the existing info from vandalism. I don't know the underlying structure, but a good revision control system would allow you to fix any vandalism.
Sometimes the original owner may have lost interest and doesn't have time for that kind of maintenance work. What happens in that case?