I have moved a topic but I have never done this:
I have a topic with like 10 replies.
The last two replies are off topic and should be moved to a different forum and become a new topic.
I thought this was possible but I don't see the option.

Go to that second to last one, click edit, than click move merge. Check move this and its replies. Thats how I split

I see the option now, Thanks.
The bad part is I was trying to move it another way. Stupid me, I deleted it in error.
Oh well live and learn.

Okay now that I know how to split. It leads me to another question.
Lets say you have a topic with three replies.
You want to move reply one and two only but leave reply three as is.
I can see this as a issue if a lot of people reply to the original topic but some in the middle somewhere are off topic and need to be moved to there own topic.

hehe.. i just tell em to get back on topic.. and leave it at that..

don't think you can split / splice chunks in between..

it's already a pain in the arse as it is

Well it is a pain using the proper method. So I thought I found a way around it but, no.
Problem with my public site is topics are around a construction code with references to code articles so when someone posts a totally different question as a reply referencing a different section of the code book. Then everybody barks because they search for things such as 680.26 and they find something that applies to 250.122.
Of course the impression from the user is the database /search is broken because it found something that does not apply.
I won't get into the few issues with the search I have.
Currently the problem is solved, the member re-posted the question on a new topic.