The Secrets to Destroying All Data on a Disk or USB Flash Drive

1. Deleting files or folders -- When you delete a file in Windows, macOS, or Linux, it only moves it to the Trash Bin. Windows, macOS, and Linux all provide easy tools to recover deleted files from the Trash.

2. Emptying the Trash Bin -- Emptying the Trash only removes a reference or "pointer" to that file on the disk. The data still resides on the drive (until the system decides to reuse that space).

All or some of the data can potentially still be recovered by any number of popular programs. (Examples include Recuva, TestDisk, EaseUS Data Recovery, and many others.)

3. Windows Reset with "delete my files" -- The tools I just mentioned can also often recover data after a Windows Reset, even if you told Windows to "delete my data".

4. Formatting a drive -- Sophisticated "forensic" tools can often retrieve data from a reformatted partition.

5. Overwriting a Solid State Disk (SSD) -- Overwriting an SSD it is not guaranteed to eliminate all data residing on the SSD. Nor is using a tool designed for wiping a hard disk drive (HDD).

6. Using an SSD data wiping program to destroy all data on an HDD -- SSD tools won't work to destroy all the data on an HDD.

7. Overwriting a USB flash drive -- USB flash drives are also known as USB memory sticks, thumb drives, or pen drives. They contain chip memory, much like SSDs.

Many web sources say you can simply overwrite a USB memory stick to delete all its data. That is not always true!

With most of them, if you merely overwrite the data -- like you would for an HDD -- you are not guaranteed to destroy all the data. I'll explain below.

1. UEFI/BIOS Utility -- Some computers come with a secure erase utility in their UEFI/BIOS configuration panels. All you have to do is access the boot configuration panels to run it. It will usually be labelled something like "ATA Secure Erase."

2. Manufacturer's Utility -- Some disk manufacturers offer free downloads of secure erase utilities for their SSDs. Unfortunately, many vendors don't provide a secure erase utility for their consumer drives.

3. Buy a Secure Erase Program -- You could buy a program like Partition Magic to securely erase your drive. But as the following alternatives show, that's really not necessary.

4. Use the Linux BLKDISCARD command --

The Linux blkdiscard command discards blocks on SSD devices, and can zero out their data.

To use it, you'll boot a Linux that includes the blkdiscard command. (If you don't have Linux installed on your computer, you can boot a Linux distribution as a Live Linux. Here's how.)

You will use the root user id to perform these actions in a terminal window:

5. Use the Linux HDPARM command --

Another way to manually direct the secure erasure of the drive by using the Linux hdparm command. (This assumes that the drive supports the ATA Secure Erase feature, which nearly all do).

To use hdparm, first you'll boot a Linux that includes the hdparm command. (If you don't have Linux installed on your computer, you can boot a Linux distribution as a Live Linux).

You will use the root user id to perform these actions in a terminal window:

6. Use the Linux NVME command --

This option works only for NVMe drives. It's an alternative to the blkdiscard and hdparm commands.

1. Download and run a free disk wiping tool --   I recommend this first option as easy, reliable, flexible, and thorough.

Example free disk wiping programs include DBAN or its competitors. These programs boot on their own (independent of your normal operating system). They overwrite the entire disk and thereby destroy all its data.

Here's a screenshot of DBAN in action:

"Disk wiping" programs usually have a parameter that dictates either light wiping (faster) or more thorough wiping (slower).

To ensure your data is truly unretrievable, use the thorough settings. This overwrites the disk several times. That ensures there is no residual trace of the original magnetic patterns of the data you're trying to destroy.

The program could run for hours -- it depends on your disk's size and speed, and how many times you tell the program to overwrite the disk. I find it convenient to run a thorough wipe unattended overnight.

2. Linux Line Commands --

Instead of a disk wiping program, you could use any of several different Linux line commands to overwrite a disk. Examples follow. In all cases, you should execute them as the root user id.

(If you don't have Linux installed on your computer, you can boot a Linux distribution as a Live Linux. Here's how.).

For a thorough wipe that eliminates any traces of the original data's magnetic imprint, you may wish to use these commands to overwrite more than once.

If you're wiping your computer's boot drive, boot a Live Linux from which to issue your overwriting command on your boot drive.

You can use the Linux line command dd to wipe a drive. These two examples show how to use the dd command to write either zeroes or random data to a drive named sd?:

if is the input file name, and of is the output file (in this case the disk you wish to wipe).

The special input file /dev/zero will automatically generate zeroes, while /dev/urandom generates random numbers. I prefer the latter to better wipe a disk.

bs stands for the block size or the number of bytes to write at a time. To speed the operation, you'll want to use some value larger than the default of 512 bytes. (That would make for a very slow overwrite operation!) These examples write 1 Megabyte at once.

You'll know that dd has successfully concluded when it returns this message to your terminal: “No space left on device” .

The wipe command securely erases either a disk or a partition. You may have to install it for most Linux distributions.

Ensure the disk partitions are unmounted, then issue the wipe command. The operand sd? points to the drive or partition to wipe, while the flag -v stands for verbose feedback:

wipe can take a long time to run because its default makes many passes. To speed it up, you can usually reduce the number of overwrites with either the -n or -Q flags. These examples make only 2 passes:

The shred command can wipe data from a drive:

The -v flag means verbose, while the parameter after -n tells how many times to overwrite the data. This example overwrites the disk 5 times (the default is 3). sync ensures all data is written to the disk to synchronously complete the operation.

You most often see shred run against a file or group of files. That usage would not obliterate all data from a disk. For example, journaled filesystems like EXT4 and XFS may retain copies of data that shred does not eliminate.