hi
how i can delet all posts for a user?
You can delete all of a users posts by going here:
Admin CP -> Users & Groups -> Users
You can then "check" the checkbox next to the user's name that you want the posts deleted from.
You can then go down to "Inline User Moderation" and choose "Prune/Delete User's Posts".
Hope this helps.
.
If you're doing this for a spammer or spambot then I suggest installing Goodbye spammer. It makes it a lot easier.