You can't subscribe to certain topics/threads. If you're talking about a bookmark, remove it. If you're referring to the "Participated" threads, you have several options available. You can remove it in your profile settings, or you can select any given thread to stay marked as read for various lengths of time, from "now" to "forever."
If you aren't sure if your post will violate the ToS, just don't post it. Err on the side of caution and this forum will live a long and happy life.