I’m afraid not. Cutting the stem off below the leaves would bring an end to your plant. Perhaps it’s time to plant it in a pot. Avocado plants grow quite large so you’ll probably need to repot it regularly.
Well, I have never done it with plant sitting in water, however I made it with my potted avocados and they all survived - moreover, thanks to such radical pruning they're now multi-stem plants and looking really good.