There are stories of Rabbis who have composed works only later to burn or otherwise willfully destroy them (Rabbi Nachman and The Kotzker Rebbi come to mind). I would understand if they had these works buried as sheimos, but what gives them the right to actually burn divrei torah?
Rebbi Nachman - Sefer HaNisraf
The Kotzker (Actually the Chiddushei HaRim)