Your posts on this forum are rambling and for the most part it is hard to tell what it is that you have in mind and what you want to know. You don't seem to even have a very clear idea of the exact facts for your hypotheticals. If you want to get real responses, try describing some specific situation (no real names, of course) — who did what to whom, when, and where. The classic stuff you learn to write if you ever took a journalism course.
Best as I can tell, your fact pattern here is that you make a post on some forum to test to see if your reputation was tarnished. You don't say, though, what it is that you posted or why you thought the post would help you achieve your goal. Then you say someone deleted your post, presumably one of the forum moderators or adminstrators, but again you don’t actually say who it was. You also do not say why the post was removed. Assuming that this was a privately owned (i.e. non government owned) site, the owners of that site have the right to decide what posts to allow on their site and what posts they will remove. So, you’d have no recourse for the removal of your post unless there is some contract between you and the site in which the site promises not to delete your posts.