When you load the sample set you can shorten the release tail.
If you have already loaded the sample set once, you have to load the organ again with
Hauptwerk > Organ > Load organ, adjust rank audio/memory options/routing ...
In the next window (Rank Audio/Memory Options and Routing) mark all ranks, which release tails should be shortened and choose Release sample truncation: . Here you can experiment with the different options until you find your personal preference.
Hope that helps!
Cheers,
Chris
BTW: This works only if the sample set producer allows to shorten the release tail.