If you click on the 3 dots under your post, you’ll see a little trash can. Click on the trash can and that will permanently delete the post without any record of what had been there before.
Please understand that, if you use this after someone’s replied to you, you risk adding confusion to the thread.
I don’t know why sometime even after 24 hours it doesn’t get deleted. Only sometime though. Maybe the forum system want to specifically embarass us or sometime.
Well you need the credentials to have then deleted sooner.
I know this as I posted in the wrong thread before and deleted the post with the trash icon, and a mod (at that time) who was around cleared it within like 30mins or so.
But if you edit the post to type something like “deleted” (not trash icon) all the history of the post remains and can be viewed.
And sometimes maybe it’s just buggy so it got stuck there.