When a file is deleted, only the file name is erased. The body of the file is unchanged. It is possible with some tools (Restoration, PC Inspector File Recovery, ...) to recover these files. SDelete allows you to overwrite the free space on a disc so that recovery is impossible.
Advantage It supports the features of NTFS and may use patterns (patterns) that prevent most of the physical recovery operations.
SDelete works from the command line.
Disadvantage You need to have knowledge to use this application.