I havent seen the backend code of LFSW, but I dont think its hard to change the kilometeres and driven laps, even though the stats for your account would not be consistent anymore (still showing the old races history for example).
I mean, the drag statistics were reset a couple years ago because of a bug. It all depends on a) how much which things intertwine with others and b) if the devs want to allow the users to get those settings changed.
You know, if one driver may change this, everyone wants. I remember the time when the German Community started to use their real names in LFS, and everyone wanted to change his account name from nick to real name. Vic was lucky he said 'no' to the first one who asked, because otherwise, there would have been a couple hundred others who wanted the same. I already saw them moaning and crying "oohhwuhhh he is allowed to get this and Im not wuuuuahhhaaaa"
:P