Remove modified date from Post

Hello!
I would like to remove the modified date which is shown between the post title and the post itself. Right now it shows (Post_date)(Modified_date) without any space in between. You can see it here:
http://greenevi.com/smashed-purple-potatoes/

It would be great if only the original posting date, not the modified one would be displayed. Does anybody have an idea how to solve this problem?

Thanks in advance