DVD-R discs are recorded by a DVD burner in your computer. A variety of free applications for burning and erasing data discs are available online. You can use the same program you burned the disc with to erase data on a DVD-R. You cannot record new data to a cleared DVD-R if it has already been burned once.
Push the "Power" button on your computer, and open the DVD burning application. Insert the DVD-R disc that you want to erase into your computer's DVD burner.
Click "Erase Disc" in the program's main menu, and select the disc drive containing your DVD-R. Click "Next." The program begins erasing all data from the DVD-R disc.
Wait for the disc erase process to complete, then click "Finish," and exit the program. The DVD-R disc is cleared of all data files.