Be sure to wipe your storage drives, laptops, smartphones, tablets, and anything that potentially contained sensitive files before getting rid of it. Whether you’re disposing of it, selling it, or giving it away, you should securely erase your data first.
This is necessary because it’s possible to recover deleted files from many types of drives. Data isn’t always immediately removed from an underlying drive if you delete it in the normal way.
USB Drives, External Hard Drives, and SD Cards
A wipe process is necessary for USB drives and external hard drives. Yes, even though your USB drive contains solid-state flash memory—and even though your external hard drive might contain a proper solid-state drive—you need to keep this in mind.
TRIM isn’t supported via the USB interface, which means someone could potentially recover sensitive files from an old USB drive after you get rid of it.
To wipe an external drive on Windows, you don’t need a special drive-wiping tool. You can just format the drive from within Windows, but you must perform a “full” format and avoid the “Quick Format” option.
This works on Windows 10, Windows 11, and any other modern version of Windows. Starting with Windows Vista, the Full Format option was changed to always write zeros to the entire drive to ensure data is fully erased.
Bear in mind that solid-state storage only has a limited number of writes. This will reduce your drive’s lifespan, especially for cheap flash drives. You wouldn’t want to do this all the time. But, if you’re about to dispose of the drive, that’s fine.
On a Mac, open the “Disk Utility” application, select the external drive in the list on the left, and click the “Erase” button in the toolbar. (You can also right-click the external drive in the list and select “Erase.”
By default, your Mac will note securely wipe the drive. To change this, click the “Security Options” button, drag the slider at least one notch to the right to that the tool says it will write a pass of random data, and then click “OK.” Select a file system for the drive and click the “Erase” button to continue.
Laptops, Desktops, and Internal Hard Drives
On a laptop or desktop, your internal hard drives only need to be wiped if they’re mechanical hard drives or hybrid hard drives. When you delete a file on a solid-state drive, the file is automatically wiped from the drive due to TRIM—this helps keep your SSD speedy.
The below tricks are only necessary if you’re using a mechanical or hybrid hard drive. Don’t do this for solid-state drives — it’s both a waste of time and will cause unnecessary wear to the SSD.
On Windows 10 or 11, you can simply choose to “Reset” your PC and tell Windows to “clean” the drive during the process. This wipes the drive, will ensure none of your files can be recovered later.
If you’re using Windows 7, Linux, or another operating system, you can boot your computer from a tool like DBAN. This tool will boot up and erase your computer’s hard drives, overwriting them with random data. You’ll have to reinstall Windows or Linux afterward before anyone can use the computer again, of course.
However, you probably don’t have to do this. Your Mac uses File Vault encryption by default, so reinstalling macOS will ensure the encryption key is removed and any scraps of files can’t be recovered. However, if you disabled File Vault encryption, wiping your drive in this way is a good idea.
Smartphones and Tablets
Apple’s iPhones and iPads use encryption, which means you can just reset them the “Erase All Content and Settings” option under Settings > General > Reset. After doing so, your personal data will be inaccessible. Any fragments of data are stored on the device in encrypted form, and no one can access them.
Modern Android phones also use encryption by default. You can restore your Android device to factory settings to wipe your data.
Because the data stored on the device was encrypted before you performed the factory reset, the data stored on the device will be scrambled and incomprehensible.
Encryption Ahead of Time Also Works
You could also just enable full-disk encryption ahead of time. When you use encryption, your data can’t be recovered without your encryption passphrase. Any bits of leftover data and other files will be on the drive in an encrypted, scrambled state. People using data forensics software won’t be able to pick out any fragments of data.
For example, Chromebooks always use encryption, so simply performing a factory reset will ensure your data isn’t accessible.
If you have a CD or DVD you want to remove sensitive files from, you can erase it if it’s rewriteable. Otherwise, be sure to physically destroy the CDs or DVDs before disposing of them. This could mean grabbing a pair of scissors and cutting them into one or more parts.