As it is, the nuclear option discussed in the comments below the JWZ post is the only option for users on Mastodon who don’t want to signal boost a reply to one of their own posts.
Deletion of the entire thread isn’t the only moderation option available to the OP on other platforms. On Elon Musk’s X.com:
Post authors have the option to hide replies to their posts. Everyone can still access hidden replies through the hidden reply icon, which shows up on the original post when there are hidden replies.
The OP of the top level post has some ability to moderate comments and replies on all of the popular platforms. X, TikTok, YouTube, Twitch, Instagram and Facebook all provide options for users to moderate replies and comments on their own posts, profiles, and channels.
Curiously, Facebook provides an option to either delete or hide.
the entire conversation is then gone, even though it might have nothing to do with your original post?
Having an entire unrelated conversation under somebody else’s post would be a breach of etiquette on most platforms. On the old forums this is “hijacking the thread” and against the rules.