Delete does not mean Erase
When we're using modern hard drives today, we're like to left traces of sensitive data on it. If you don't want them kept in wrong hands, it is better to wipe them clean when you don't want to use it. If you're the media contains valuable corporate trade secrets, business plans, personal files or confidential letters, you must know that the delete operation does not mean data erase, wipe or overwrite which should not be recovered. Like we mentioned in the previous situation that when you leave you job you want to wipe out the personal browse history of on the computer.
When you press the delete button, or delete files from the right-click menu, Windows does not erase the file contents from sectors that keep them– it only deletes the reference on the file from some system tables. The details remain on the hard drive unless another file you downloaded/created overwrites it. But if these sectors stay the same or new files will not come, details of the previous files and folder can still be found and recovered by any data recovery software you might come across.
Erase, on the other hand, is to overwrite the left sectors you deleted files and folders. Ones and zeros are filled in the deleted free space, they mean nothing to the system and data recovery programs and they are the numbers to replace sectors with traces. However, erase is not the default function in Windows, you may find that after Windows 10 released, you can find the option Erase everything and keep system when you restore computer, but that option erase everything on the disk except the system, it may not satisfy you when you just wanna erase free space instead of the entire disk.
ByebyeData Eraser can fulfill your requirements of erasing free space, individual files and folders. Even the entire disk, contains system or not, can be erased by this wiping software. We have a guide page on how to wipe a computer and here is the main interface of ByebyeData Eraser, you can free download it and give it a try.