You can delete your own discussions if you really wanted to. Just contact mylot and ask them to delete your discussion and provide the link to the discussion. They will usually delete it within the next day.
This was referring to your own DISCUSSIONS not your own responses.
For responses I agree that you either contact myLot or ask the owner of the discussion to hit the (!) beside the response concerned and ask for it to be deleted.
Nope that is not a delete button that is a delete request giggle giggle giggle.. But I didn't know that you could request to have a discussion deleted what I really want is an edit button to edit discussions after you posted them...