Because of the way file systems are designed to work in Windows and other operating systems, the contents of the files stay behind even when the files are deleted. In order to completely and thoroughly erase the contents of the files when they are deleted, you must securely delete them using a tool like File Shredder.
File Shredder is a secure file erasing tool that can damage the contents of a file before deleting it. This ensures that the deleted files can never be recovered from the hard drive. In order to damage the contents of the files, it uses some algorithms designed by the scientists and cryptographers working for some of the well known organizations like United States Department of Defense (US DoD). A method from the famous computer scientist Peter Gutmann has also been included.
The user interface of File Shredder is very simple. You just have to drag-n-drop your files (that you want to securely erase) on the File Shredder window and then click on the Shred Files Now button. After a brief confirmation, it will completely shred (destroy) the contents of those files before deleting them.
As mentioned before, it comes with many different methods used for shredding files. You can choose one or other method. There are faster methods and there are very secure but slower methods like the Gutmann 35 pass method (a file is processed 35 times before deletion). You have to select these methods from File Shredder settings.
Apart from file shredding, the program is also able to securely erase empty space on your hard drive which may possibly contain some of the remnants of previously deleted files. Overall, the program works well in Windows 10 and even adds a context-menu handler for the File Explorer so that you can right-click on files and shred them.
You can download File Shredder from https://fileshredder.org/.