Hubert, when you add a discussion on someones profile the discussion is also added to the list of all public discussions. But it's not clear what you want to discuss. Probably you just wanted to add some remarks / additional information.
22/12/2011 at 11:35 ÖS
There is a delete link to the left of your message under your name and timestamp of the message. When last message is deleted the topic will go away.