There are time locks in the forum to stop deleting or modifying of posts after a certain time.
Assuming the post has been made recently any options that are still available should be listed against the post in the top right of the post when viewing the topic.
Suggest that modifying or deleting should only be used when it is vital to do so as it can confuse other users or a response made may not make any sense due to a missing post.
Duplicatation of posts however does make sense to remove one!
