How in the everlasting fuck is it legal tp use these machines for elections?
KEK
Deleting files from a disk doesn't really delete them, it just marks them as deleted and deallocates the memory they use on the disk. If you've got a spinning harddrive and want to delete shit, you can use a software that wipes files by overwriting them according to some DoD standard I don't remember offhand. But note that this stuff doesn't work for SSDs, at all. The only real secure way to wipe files off of flash memory based storage is to physically destroy the memory device.
This is bad advice. Allow me to explain why:
Flash memory controllers use very clever algorithms to minimize repeated write operations to any single flash memory cell. This is to mitigate the fact that flash cells are prone to die after a bunch of write operations. This means that, if you write to the same block repeatedly, each of the writes will end up going to totally different physical flash cells.
Additionally, the controller puts aside reserved space that it will use for remapping of broken flash cells. Remapped memory becomes completely inaccessible to the end user. The contents of these reserved memory areas can however be revealed through forensic methods.
This all means that any software trying to wipe stuff off of flash memory will well reduce the overall lifetime of the flash memory device, but not actually succeed in wiping anything off of it. And the fact that stuff may get remapped into inaccessible areas further complicates the matter.
Some SSDs offer a low level command that supposedly tells the controller to zero out all the flash cells. It's anyone's guess if that even works as described.
If you want to securely delete files on a flash memory based device, you'll have to physically destroy the device.