How to wipe a computer before selling, donating, or recycling it

Before you wipe anything

1. Back up your files. Once the wipe finishes, they're gone for good. My backup and transfer guide walks through it, including the stuff people forget, like saved passwords and license keys.
2. Save your license keys for any paid software you'll reinstall on another PC.
3. Sign out of your accounts: your web browser, OneDrive, iCloud, and anything else that syncs. Deauthorize software with install limits, like older Adobe or iTunes.
4. Remove the PC from your Microsoft account. Go to account.microsoft.com/devices, find the computer, and remove it so it's not tied to you anymore.
5. Leave the charger and any accessories you're including with the PC. Take out any USB drives or SD cards you forgot about.

Wipe a Windows 10 or 11 PC with Reset this PC

Windows has a good wipe built in. The key is one setting most people skip.

1. Open Settings → System → Recovery on Windows 11, or Settings → Update & Security → Recovery on Windows 10.
2. Click Reset PC (or Get started under Reset this PC on Windows 10).
3. Choose Remove everything.
4. Pick Cloud download or Local reinstall. Either is fine. Cloud download gets a fresh copy of Windows.
5. Click Change settings and turn on Clean data. This is the important part. Without it, Windows just deletes the files, and recovery software can often get them back.
6. Confirm and click Reset. With Clean data on, it can take a few hours on a big hard drive. Let it run.

When it's done, the PC boots to the Windows setup screen, ready for its next owner. Stop there and shut it down. Let the buyer set it up with their own account.

SSDs need one more step

On an old spinning hard drive, overwriting the data really does erase it. SSDs work differently. To keep from wearing out, they spread writes across spare memory cells, and an overwrite can miss some of the cells where your old data still sits. Clean data is still worth doing, but on an SSD it's not the whole job.

The simple fix is to encrypt the drive before you reset it. Then anything the wipe misses is scrambled and useless without a key that no longer exists.

1. Search the Start menu for BitLocker (Windows Pro) or open Settings → Privacy & security → Device encryption (Windows 11 Home, on PCs that support it).
2. Turn it on for the C: drive and let it finish encrypting. That can take a while.
3. Then do the Reset with Clean data above.

Not sure which kind of drive you have? Open Task Manager, go to Performance, and click Disk 0. It says SSD or HDD in the corner.

Better yet, use secure erase in the BIOS

Many business laptops and desktops from about 2019 on have a secure erase tool built into the BIOS, the setup screen you get to by pressing a key like F1, F2, or F10 at startup. It tells the drive itself to erase everything, including the spare cells, which is what the pros use for SSDs.

• Lenovo: look for ThinkShield Secure Wipe under the Security menu on newer ThinkPads and ThinkCentres.
• Dell: look for Data Wipe under the Maintenance menu on newer OptiPlex and Latitude models.
• HP: look for Secure Erase under the Security menu on business models.

This wipes the whole drive, Windows included, so afterward you'll need to reinstall Windows with Microsoft's free Media Creation Tool, or leave it blank for the buyer. Not every model has it. If yours doesn't, the encrypt-then-reset method above is plenty for a home PC.

Wiping a separate hard drive

For a spare internal or external hard drive (not an SSD), Windows can do it without extra software:

1. Plug the drive into a working PC and open File Explorer.
2. Right-click the drive and choose Format. Uncheck Quick Format.
3. Click Start. A full format writes zeros over the entire drive, which is plenty for a hard drive you're selling or donating.

Double-check the drive letter before you click Start. A full format can't be undone.

If the computer won't turn on

A dead PC still has your data on its drive. You've got three options:

• Pull the drive and wipe it from another computer with a USB adapter (about $10-15), using the steps above.
• Destroy it. For a hard drive, drilling a few holes through the platters does the job. For an SSD, break the circuit board, making sure you crack the memory chips.
• Use a recycler that wipes drives. A good one can tell you exactly how they handle drives and give you a certificate if you ask. That's how I run my own pickups.

Don't just toss it in the trash. Besides your data, electronics don't belong in a landfill. If you're near Topeka, here's where to recycle electronics in Topeka, Lawrence, and Manhattan.

What "NIST 800-88" means, in plain English

NIST Special Publication 800-88 is the U.S. government's guide to wiping storage. It's what businesses and recyclers follow. It sorts every wipe into three levels:

For a PC you're selling to a stranger, aim for Purge if you can, especially on an SSD. For a computer you're handing to family, Clear is usually fine. Businesses with sensitive data should use a recycler that documents the method and the drive's serial number for each device.

Wiping a Mac

On Macs with Apple silicon or a T2 security chip (roughly 2018 and newer), go to System Settings → General → Transfer or Reset → Erase All Content and Settings. It wipes the Mac's encryption keys and signs you out of Apple services in a few minutes.

Older Macs, like the 2013 "trash can" Mac Pros I have, don't have that option. Sign out of iCloud first, then boot into macOS Recovery, erase the drive in Disk Utility, and reinstall macOS.