How to Completely Wipe All Data From Your Computer

Whether you’re selling it, trashing it, or reusing it, your old computer has a bunch of extremely private data stored inside. And there’s a good chance that tossing files in the recycling bin and hitting factory reset won’t protect you. If a hacker finds the pattern your computer used to move those 0s and 1s around, they can reverse engineer the original state of your computer and pull out the goods.

To stay safe, you need to properly factory reset your computer before it ever changes hands. Follow the steps below, or consider taking things a step further by hiring a professional company to ensure your data has been destroyed.

What Is a Factory Reset?

A factory reset means deleting anything that wasn’t on the device after it came out of production, so this will definitely make it impossible for you to practically access programs or files on your computer.

It’s important to know what a factory reset actually does, though. It puts all applications back into their original state and removes anything that wasn’t there when the computer left the factory. That means user data from the applications will also be deleted. However, that data will still live on the hard drive.

Factory resets are simple because they’re programs included on the computer when you first get your hands on it. It’s useful to reset errors with an operating system or helping restore the computer’s functionality or speed.

There are limitations, though. Factory resets leave data in the hard drive, so those pieces will live on until your hard drive is overwritten with new data. In short, the reset can give you a false sense of security. A complete erasure would actually look more like degaussing (destroying the magnetic field around a hard drive to destroy its data), or actually smashing up the hard drive to bits.

Context is still key. If you only ever really played games or finished schoolwork on your computer, there’s probably little risk in using a factory reset as your primary form of data wiping.

But if you own a company and complete that work on a computer, you may have employees’ social security numbers on the hard drive, for example. That means you should probably consider hiring an expert to finish the data wiping, especially because the government has certain standards for data sanitation, depending on the field you work in.

How to Factory Reset a Mac

Make sure you’ve backed up all of your important data in a cloud service. For a primer on cloud services, click here.
Log out of all services that you use.
Make sure your computer is plugged in for the duration of the reset.
Restart in Recovery Mode: Click and choose Restart. When the computer shuts off and powers back on, hold Command + R until you see the Apple logo.
You won’t see your usual login page, anymore, but instead will see a “macOS Utilities” window.
1. Choose disk utility > continue.
2. Choose the correct startup disc and select erase.
3. Choose MacOS Extended (Journaled) as the format.
4. Click erase
5. Wait until the process finishes, then go to the Disk Utility menu > quit.
If you like, reinstall MacOS.

How to Factory Reset a PC

Repeat steps 1-3 as listed above.
Navigate to Settings > Update & Security > Recovery. You should see a title that says “Reset this PC.” Click Get Started.
You can either select Keep My Files or Remove Everything. The former reset your options to default and removes uninstalled apps, like browsers, but keeps your data intact. The latter, as its name suggests, will delete your files. In either case, back up your files in case something goes awry.
Use the Fresh Start option in Windows 10: Settings > Update & Security > Recovery page, Then, click the link text “Learn how to start fresh with a clean installation of Windows at the bottom. That opens a Windows Defender Security Center window to the Fresh Start option. Click Get started.

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Why a Reset Sometimes Isn’t Enough

Inside your hard drive are two rotating discs that sort of resembling a CD. These are called platters, and they’re the pieces of hardware that actually store all of those cat videos and family photos.

The platter stores data onto its circular surface in chunks of 1s and 0s. Platters are usually ceramic, glass, or aluminum, and work as a record player. Centered on a spindle, the platter rotates and an electronic current reads and writes data onto the surface. Electronic components power the whole operation.

When you delete data from the computer through a factory reset, the information is hidden from the computer, but still stored on the hard drive. If a hacker uses data forensics tools, they can find bits and pieces of those deleted files in the hard drive storage, making it possible to recover pretty much everything.

There’s much online debate about the best ways to completely destroy the data inside, but most solutions come down to the water, hydrochloric acid, magnets, or a blunt object you can smash them with easily.

These methods might sound hardcore, but three of them still aren’t completely reliable. Microwaves often don’t get hot enough to properly wipe the platters. Acid doesn’t seep deeply enough inside the discs to ensure complete destruction. Hackers have recovered laptops thrown into bodies of water and dug data out of the hard drive afterward. Magnets aren’t always strong enough.

But smashing the platters is a different story. Just make sure you wear safety glasses because the platters often break into tiny shards when smashed. Remember: the key to destroying the platter properly is ensuring it can’t spin. If it can’t do that, the platter’s contents can’t be read.

If you do want to reuse the hard drive, a factory reset should be your course of action. As stated above, first be sure you don’t have any comprising information on the hard drive, because it could take a long time for new data to overwrite all of the old data on the drive.

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