In-depth

How to wipe a laptop easily and securely

Selling your laptop? Make sure that all your sensitive data is gone before it reaches its new owner

A male hand switching on a laptop computer

Laptops can reveal a lot about a person, and we’re not only referring to how well they are maintained. In fact, these popular devices are a minefield of information about their owner, and can oftentimes be used against them. 

Anyone who has ever had their laptop stolen can understand the immense trouble that follows. Filing a police report and having to spend a few hundred pounds on a new device are often only the tip of the iceberg, especially if the stolen laptop contains sensitive information such as phone numbers, addresses, and credit card details. If the laptop was taken while it was unlocked and you allow your browser to remember login details, the criminals can also easily gain access to your banking account or any social media platforms. This could pose a real risk of not only financial theft, but also identity theft, with criminals potentially using your personal information to commit fraud or other crimes.

Given all these threats, no one wants their laptop stolen. However, this kind of personal data can also be obtained by strangers without having to steal it. For instance, you might be selling your old device, or returning it to your company’s IT team, who in turn will give it to a new joiner. This is why it’s always important to wipe your laptop before you let go of it for good – and no, we’re not just talking about wiping the screen with a cloth.

In this guide, we’ll show you how to clean your device off any data. This is in order to protect you from any data thefts, as well as ensure that your company isn’t subject to any breaches which could result in an expensive GDPR fine.

Back up important data

The first thing you must do is to ensure all of your files and folders are backed up and organised, do you don't wipe anything that you may need at a later date. Even if you don’t think you’ll ever access the data in future, you may need to reference something hidden away in archives in the distant future.

There are a few ways of doing this and the most practical for you will depend on how much data you need to copy. If you are backing up files selectively, or there aren't many of them and you have a fairly good internet connection, then backing up to the cloud is an option.

The most complete and quickest way, however, is to back up to an external hard drive that's directly connected to the laptop.

You will need to figure out how much storage you need. If everything is stored on one drive (usually the C: drive in Windows, right-click on the drive icon to see how much data is taking up space there.

Once you have connected the external drive to the laptop you want to wipe, you can check that it is big enough to store all the data you need.

To backup, you can simply connect an external drive to the laptop and drag files and folders to it. You can use the Windows Backup feature in Windows 7 of File History in Windows 8. Windows 10 has both features and adds the ability to backup and restore system images. 

How to wipe a Windows 7/Vista/XP laptop 

Wiping a laptop running Windows 7 shouldn't be too difficult. Although the legacy OS is now obsolete, you might still encounter older devices with the OS still installed.

You can use an application such as DBAN (link). It's downloadable as an ISO image but you will need to extract it onto a bootable USB or disc in order to use it as a boot device.

Once this USB flash drive is inserted in the laptop you want to wipe, restart the machine and then boot from this drive from the BIOS screen. From here you simply follow the prompts and wait for the machine to work through the reset process, which will securely delete everything. You can now reinstall Windows 7 from any disc or bootable USB stick with Windows installation files.

DBAN can also be used to wipe any drive running Windows or indeed Linux as it doesn't need to run in any particular OS.

How to wipe a Windows 8/8.1 laptop

It's much easier to wipe a hard drive in Windows 8 or 8.1. Head to the Start screen, find the Charms bar, click on Settings and then hit Change PC settings. Finally, choose Remove Everything and Reinstall Windows.

When you choose to erase data, make sure you click on the "thoroughly" option rather than "quickly", just to be sure that everything is deleted.

How to wipe a Windows 10 laptop

Reset page on Windows

You're able to wipe the hard drive and installing a fresh copy of the OS on Windows 10 thanks to its built-in method.

Simply go to Start>Settings>Update & Security>Recovery and click Get Started and choose the applicable selection. In order to restore Windows 10 back to a pristine state, you will have to follow the set of instructions that can be found in the applicable selection you just clicked on. In this case, choose the Remove Everything option to, surprisingly, get rid of everything. If you have more than one drive on your laptop, you will be asked if you want files removed from all drives, and as a safety option, this is the best method.

Lastly, you will be asked if you want to clean the drives. This will take a few hours but will make sure that there are no files recoverable from the disk.

How to wipe a Mac

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Wiping a Mac has broadly similar principles but is, in fact, a lot easier to do, no matter what version of macOS you're running - from Mountain Lion to Mojave. A system disk isn't required, but for earlier Macs you will need one. To initiate the recovery partition, hold down the command and R keys as the computer restarts and open Disk Utility.

Search for the Erase tab security options and click 7-pass Erase. This will write the data to the disk several times. It might take a few hours to complete the process but is a very secure way of doing so.

How to wipe a Linux laptop

If you've got a Linux-based machine, wiping any of the hard drives - internal or external - is a slightly fiddly process that involves using the command line.

Open up a command line terminal and enter 'sudo fdisk -l'. This will list all the storage drives currently connected to your machine. Find the drive you want to wipe, and note the drive's device path.

Next, run this command - 'sudo dd if=/dev/zero of=/dev/sdb bs=1M' - via the terminal, making sure to substitute '/dev/sdb/' with the target drive's correct device path. This method is known as 'zeroing', and wipes the drive by overwriting every byte of information with zeroes.

There is some debate as to whether or not this is more secure than overwriting the drive with random bits of information, but it's usually quicker and is perfectly sufficient for protecting your data from the average buyer.

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