Deleting a file doesn’t remove it — the data remains until overwritten. Secure file shredding tools overwrite deleted files to make recovery impossible.

Why Normal Deletion Isn’t Secure

When you delete normally, only the file system pointer is removed — the actual data sectors remain on the storage device. File recovery tools can easily restore ‘deleted’ files.

Recommended Tools

Eraser (Windows): Free, open-source, integrates with Windows Explorer. Supports DoD 5220.22-M and Gutmann (35 passes). Schedulable tasks for automated deletion.
FileVault Secure Delete (macOS): On APFS drives, enabling FileVault means deleting a file makes it cryptographically inaccessible without the key.
Shred (Linux): Command-line tool on most distributions. Supports multiple overwrite passes.

SSD Considerations

Modern SSDs with TRIM make secure deletion less reliable. Full-disk encryption (enabled at setup) is the best solution for SSDs — encrypted storage is unreadable without the key.

Conclusion

Enable full-disk encryption first. Then use Eraser (Windows) or FileVault secure delete (macOS) for targeted file shredding.