I've never thought about this before, but I don't think you can. At least I haven't found a way to do it.
One "solution" could be to create a sub-profile and use that (assign all DVD's to that) and not fill out the Taste Preference for that profile, if it's important enough to you.
Or you could call Customer Service (1-866-716-0414) and see if they can clear them (I doubt they can, but I guess it's worth a shot).
I simpy chose the "middle" option for everything. I guessed there's not much they can determine from that.
end of summer should be able to do something like that. according to the netflix people
Gargle with a warm salty beverage of your choice.