I've used this feature a few times to do exactly what you're hoping for.
As an Admin or Mod with "Edit any post" permissions (bottom-right at Control Panel > Forum Permissions);
1. Click "Edit" on the individual post you want to move. Not the OP, but the one which is OT. 2. Click "Move/Merge this post and any replies." 3. Select the top option, "Move post & replies to:" and from the drop-down list, choose the forum you want the post and its replies to be moved to. 4. Click submit.
SEE ATTACHED IMAGE
[EDIT] Giz, are you asking for an option to "Move Single Post" WITHOUT its replies?
ALTERNATIVELY: Edit the user's post to replace its text with something such as:
--- ADMIN EDIT: Off-Topic Post Removed. To increase the discussion quality, it is imperative that we eliminate "off topic" posts, and those which derail the current discussion topic.. --- OR --- ADMIN EDIT: Trolling / "Off Topic" Post Removed. To cut down on the abuse and to increase the discussion quality, it is imperative that we begin to eliminate "off topic" posts, and those which are obviously posted for the intent to troll. ---
