How can I securely delete a file to prevent recovery on Windows?

Secure deletion requires overwriting the file's data before removal, making recovery impossible. Tools like Sysinternals SDelete (`sdelete64.exe C:\test.txt`) perform this overwrite. Alternatively, you can write a C++ program that fills the file with zeros or random data before calling `DeleteFile`, as shown in the article Penetration Techniques - File Recovery and Deletion in Windows Systems. This ensures even if the MFT entry is restored, the content is meaningless.