cipher /w:Xwhere X is a drive letter. It needs to be run as Administrator. It takes a long time but ever other alternative does too. Make sure you empty the Recycle Bin before running it. Cipher's help (cipher /?) says its for NTFS but /w works on FAT32. CIPHER.EXE is included in XP Professional but not Home Edition. You can also use BleachBit or CCleaner.
Computer Tips - How can I securely wipe the deleted files on my Windows PC?
Date: 2015mar13 OS: Windows Keywords: Windows, wipe, freespace Q. How can I securely wipe the deleted files on my Windows PC? A. There is a now a command-line utility that can do that.