If you want to get rid of everything on the drive, right-click the Start button, click "Explore" and right-click on the D drive. click "Format" then click "Quick Format" then "Start."
It takes only a few seconds to complete.
If you want to delete only certain files, right-click the Start button, select "Explore" then click on the D drive and look around at files and folders you don't want. Right-click them and select "Delete" and they will be deleted.