In the instructions in MN 20 step 2 is to regard the thought as a danger and be horrified and humiliated and disgusted. MN 61, near the end has the most targeted instruction for a good wholesome purpose for the energy generated in the case when your subconscious brings up a mistake you have made in the past. that is to generate horror that you made the mistake, then humiliation with the area of the mind that allowed, or please forbid contributed to the mistake. Then dedicate the humiliation energy to future restraint. See this article for the dangers in using this tool.