Wiping a phone or laptop before you sell it

Dragging your files to the bin does not remove them. What does work is the built-in reset, because on any device made in roughly the last decade the storage is encrypted and a factory reset throws away the key. That makes what is left unreadable rather than merely deleted.

The order matters, because a couple of the steps cannot be done after the reset.

Before you reset anything

1. Back up. Once it is gone it is gone.

2. Sign out of your accounts, on the device. This is the one people skip and it is the one that causes trouble:

• iPhone or iPad: Settings, your name, Sign Out. This turns off Activation Lock. Skip it and the

buyer gets a device permanently locked to your Apple Account, and you will be hearing from them.

• Mac: sign out of your Apple Account, and turn off Find My.
• Android: remove your Google account in Settings, Accounts, or Factory Reset Protection does

the same thing.

• Windows: sign out of your Microsoft account.

3. Turn off two-factor tied to the device. Move your authenticator app to the new phone first — its codes do not transfer by themselves, and this strands people out of their own accounts more often than anything else on this page.

4. Remove the SIM and any memory card. Obvious, routinely forgotten.

5. Unpair your watch, if the phone is paired to one.

Then reset

• iPhone or iPad: Settings, General, Transfer or Reset, Erase All Content and Settings.
• Android: Settings, System, Reset, Erase all data.
• Mac: Apple menu, System Settings, General, Transfer or Reset, Erase All Content and Settings.
• Windows: Settings, System, Recovery, Reset this PC, Remove everything — and choose **clean the

drive** when it offers, which is slower and thorough.

The exception worth knowing

An old mechanical hard drive is different. A spinning disk in a laptop older than about 2015 may not be encrypted, and a reset there does not make the data unreadable. If it holds anything that matters, use a wiping tool, or take the drive out and keep it. A drive is cheap; a decade of documents is not.

The same applies to an external drive or a USB stick you are passing on. Encrypt it or destroy it.

Things that are not devices but hold your data

Worth a thought before they leave the house: a car's infotainment system with your contacts and home address in it, a games console signed into your accounts, a printer with a hard drive, a smart TV signed into everything. Each has a factory reset. Each is routinely sold with all of it still there.