File Shredder is a reliable tool that can be used to shred files. It is available for free under a GNU licence. You may download File Shredder and use it without any restrictions. File Shredder is a powerful program that shreds files with the option of 5 different shredding algorithms, each slightly stronger than the previous. Additionally, File Shredder has an integrated Disk Wiper which uses a shredding algorithm to wipe unused disk space. More information may be found at the File Shredder Website.

Shredding Files Using File Shredder

1. Install File Shredder from the link above.
2. Open File Shredder.

       3. Select the files you wish to shred by clicking "Add File(s)" or "Add Folder."

        4. Once the files have been added, click "Shred Files Now.."

For additional assistance using File Shredder, please check their Online Help page.

The ability to securely delete files is built into the OS on Mac computers.

To securely delete a file:

1. Add the file to the Trash Bin. 
2. Choose Finder from the menu bar.
3. Click "Secure Empty Trash..." When you do this, not only is the file removed from the Mac’s directory, but the hard drive space it occupied is overwritten with random binary digits.

You may also adjust your settings so that files are removed securely each time you empty the trash. To adjust this setting:

1. Click Finder from the Menu Bar.
2. Select Preferences.
3. Click Advanced. 
4. Check the box to "Empty Trash securely."