[HOW TO] Remove some posts from topic
 

Hi
We are trying to cleanup our db and delete some post. Now we need to keep first + last posts of a topic and remove all other posts in topic. For example we have a topic with 10000 posts and we dont want to keep them . Just we want to keep starter post and last post of topic. How can we do this faster that the topic url will keep the same number (because SEO).
I have to split topic? move posts? which way?

Thanks in advance