it's not very nice or helpful to delete your posts's content like this; probably doesn't inspire people to want to help you or contribute to your threads in the future.
usually makes the rest of any threads this happens to useless for anyone else that might have been looking for information to help them, because even if the replies are there, context and related info is now lost.
it would be much much better to simply add the comment you replace your post with as a new post, and then leave the original post as it is.