Only in the first 15 minutes or so by using Edit. Vishal will be along shortly to fix it if you report it yourself, lol.
No you cannot delete them. Like Just2Ez said, you can edit your posts within 60 minutes. I have fixed your post.
You can post and then edit it. Some forums will allow you to delete your post even though others have posted there already. I am referring to threads that you have started.