sdelete — Securely delete file/directory from disk, or clean the free space on a volume/physical disk. More in

Delete files with 3 [p]asses

sdelete -p 3 {{path\to\file1 path\to\file2 ...}}

Delete folders and its [s]ubdirectories with 1 pass (default)

sdelete -s {{path\to\directory1 path\to\directory2 ...}}

Clean the free space of volume D: with 3 [p]asses

sdelete -p 3 D:

Clean the free space with [z]eros of physical disk 2, which should not contain any volumes to be cleaned

sdelete -z 2