If your the creator of a topic, you have the right to remove it. This will delete all the responses to it, but that's generally a sensible thing, as the comments are out of context without the original post.
As for pictures, you can "modify" your post and take out the link to the picture if you want to keep the post but remove the picture.
I wouldn't worry too much about affecting people's post counts - we're all way more concerned about our reputation points
. Hmm, I assume that removing a post that has a reputation point linked to it will not affect the reputation point itself - I'll check on that.
