Windows 7 - Delete video file history in DVD Maker

When using windows dvd maker, I click on add items button to add video to make a dvd, the next screen opens up which is my video Library. At the bottom of the screen is the file name screen. When I click on the arrow at the end of the screen it shows all of the previous files I used to make previous dvds. My question is how to delete that history of files used to make previous dvds?