Shred File
Shred File deletes one or more selected files (or a single selected folder) instantly and securely, preventing them from being retrieved from the hard disk using file-recovery tools. Selected files are overwritten multiple times by dummy data and then erased from the disk.
Just select and right-click the files or folder you want to delete, choose Shred File/Folder from the shortcut menu, and choose OK in the confirmation prompt. (Due to the nature of this tool, a confirmation prompt is always shown before any files are shredded.)