Yes. This can be accomplished in one of two ways:
- Delete the question. This is probably obvious.
- Put a historical lock on the question. This is a special status that moderators can place on a given question, which will preserve it and all of its answers on the site but prevent any future modifications. It will also remove it from all default lists - you'll still be able to find it by searching for it, but it won't show up to casual readers.
Option #1 is preferred for questions that have simply outlived their usefulness. Option #2 was created explicitly for questions that are/were enjoyable and worth keeping around as a reminder of the site's history, but which shouldn't normally be held up as examples of good questions.