To delete a post, first make sure you're in the content area with the menu along the top left.

Then select the post form the list along the left, the preview will be generated to the right:

You can now use the "edit" pencil in the top right hand corner of the preview box to re-enter the create a post page with that post.

You can also use the "gear" icon to make quick changes to the post URL, publication date or simply delete the post: