With File Shredder you can remove files from your internal/external/USB hard disk drive without fear they could be recovered in any way.
Actually, the “delete” operation in Windows only removes bits of information from files so they appear deleted in OS. It is easy to retrieve those files using specialized file recovery software.
In order to remove, or shred files permanently from your system you have to use File Shredder, that is capable of rewriting the files with random series of binary data multiple times.
This process is often called shredding. That way, the actual content of the file has been overwritten and the possibilities to recover such a shredded file are mostly theoretical.