If you don't want to physically destroy the hard drive, there are several software tools you can used to wipe out your data. They do a lot better job that a simple reformat.
After erasing all data, you will probably need to FDISK and then FORMAT if you want to leave your disk bootable.
The answer to ensuring an SSD is never used again, according to Backblaze, is simply encryption. Perform a complete drive encryption using reputable encryption software, such as Apple's FileVault or Microsoft's BitLocker, and then forget the passphrase to decrypt it!
Wipe Entire Disk Drive = Shred the Whole Volume = not just files and folders and free space
To remotely wipe your device, you must first have iCloud configured and have Find my iPhone enabled; then, log into your iCloud account and select Find my iPhone from the list of web apps. Once you’ve opened the app, you’ll see a list of devices that have Find my iPhone enabled from which you can select the device that you would like to erase. Once selected, your device will be first located, then you’ll have the option to view more details about the device. Click the i to view more information, and from this window you can remotely wipe the device.
DBAN = Darik's Boot and Nuke (Hard Drive Disk Wipe) - an open source external block overwrite utility - $0
Boot & Nuke is not NIST certified per NIST 800-88 to meet legal requirements, nor could it be, since it is an external disk wiper.
Secure Erase is SIGNIFICANTLY faster and completely compliant with U.S. gov standards and practice
It's an old myth that magnets will ruin the data stored on a hard disc, because floppy discs were prone to getting scrambled this way. But most modern hard drives are safe unless exposed to laboratory-grade degaussers. Flash storage like SD and CampactFlash memory cards are also not magnetic, so are safe from data loss caused by magnets.
You can use SDelete both to securely delete existing files, as well as to securely erase any file data that exists in the unallocated portions of a disk (including files that you have already deleted or encrypted).
Copy the downloaded file, HDDerase.exe onto the created floppy/CD-ROM bootable DOS disk. Boot the computer in DOS using the bootable disk. Make sure to set the correct boot priority setting in the system BIOS. Type “hdderase” at system/DOS prompt to run HDDerase.exe.
Secure Erase, a set of commands embedded in most ATA drives built since 2001.
If this is so wonderful, why haven’t you heard of it before? Because it’s been disabled by most motherboard BIOSes.
Secure Erase is already built into ATA disk drives. This utility is free and non-commercial. SE is part of the ATA standard.
Secure Erase overwrites every single track on the hard drive. That includes the data on “bad blocks”, the data left at the end of partly overwritten blocks, directories, everything. There is no data recovery from Secure Erase.
To erase my onboard SATA drive? - some BIOS configuration may be required. Since hdderase.exe only detects drives on the primary and secondary IDE channels (P0, P1, S0, S1) the BIOS must be configured so that the SATA drive is detected one of these channels. This can be done by switching the SATA drive from “enhanced mode” to“compatibility mode” in BIOS (compatibility mode is sometimes called “native mode”or “IDE mode”). E.g. BIOS >> IDE configuration >> onboard IDE operate mode>> compatibility mode. Note - not all BIOSs support this feature.
Secure erase isn't included on SCSI drives.
Mac users already have a similar option under the Finder: “Secure Empty Trash”. And with Disk Utility you can perform a secure erase of all drive free space.
Secure Empty Trash just overwrites the files that you have in the trash. That is why the "Erase Free Space" Disk Utility is needed as well.
The only way to really ensure that sensitive data can't be retrieved from a hard drive is to destroy it. Smashing it with a hammer works for me.
HDDerase.exe is a DOS-based utility that securely erases "sanitizes" all data on ATA hard disk drives in Intel architecture computers (PCs). It offers the option to run the drive internal secure erase command, security erase unit, based on the ATA specification by the T13 technical committee.
To run the utility make a floppy, recordable CD-R, or USB DOS bootable disk; then copy HDDerase.exe to the bootable media. Reboot the computer with the floppy, CD-R, or USB inserted, and type "hdderase" at the system DOS prompt. Make sure to set the correct priority boot order in the system BIOS, such as first boot floppy, CD-R, or USB depending on which media is used to run HDDerase.exe. HDDerase.exe must be run from an actual DOS environment and not a Window based DOS command prompt environment.
NOTE: For laptop users, please make sure that there is sufficient battery life to run and complete the secure erase procedure. Secure erase may take as long as two hours for larger capacity drives. If power is lost during the secure erase, the drive will be in a locked state, preventing all I/O access. See the FAQ for further discussion on this topic.
HDD Erase - Disk Drive Secure Erase for User Data - University of California, San Diego - $0 - hdderase.zip
It's no secret (or at least, it shouldn't be) that when you delete files or folders in Windows, they're not actually erased—the space they took up is simply marked as "available for use," which allows the files to be recoverable (with the right software) until they're overwritten with new data.
There is a utility built-into Windows 7 (even XP Pro and Vista) that will overwrite all the free space on a hard drive, insuring any files you've deleted stay dead. Launch a command prompt and type cipher /w:X where X is the letter of the drive or partition you want to wipe. Be patient—the process can take a long time if you have a lot of free space.