remove posts

how can I remove other members posts from my forum?

Find any post/topic, and click the delete button.

how to delete all ?

Do you mean you wanna delete absolutly all the posts all your members have written at the same time?! Well, I think that's impossible. You have to delete one and one post.

You can go to moderation tool and check the ones you want to delete then press delete

remember once you delete a post you cannot get it back.
So you may want to set up a trash board to move them to in case you ever had to retrieve it?