cipher /w c:/MYAPPDATANote: The cipher command permanently removes data and so takes awhile according to the amount of data you’re overwriting.
The Cipher tool can overwrite deleted data in much the same way the Secure Empty Trash or Secure Erase options work in OS X. To do so, use the cipher command along with the /w switch while all programs on the system are quit. Then, from a command prompt use the /w switch followed by : and then the path to the location you’d like to overwrite. For example, if you deleted a folder from the c:/MYAPPDATA folder, you would use the following to remove data not allocated to files or folders: