Under the Solutions tab, you would find the Drafts on your account listed at the right pane of the page. 

You can click on any of these drafts which would take you to the Solutions edit page. On that page, at the bottom-left, you will find the 'Delete' option. 

You will have to re-enter the title of the article for confirmation of deletion - this is to prevent any accidental deletion of articles. 

Please note that this action cannot be undone.