Selling or donating an old device is the responsible thing to do. Handing over your tax documents, saved passwords and ten years of photos along with it is not. The uncomfortable fact: dragging files to the trash and emptying it does not destroy data. It just tells the system that space is available. Until something overwrites it, recovery software – free, point-and-click recovery software – can bring much of it back. Researchers who buy second-hand drives regularly find bank statements, medical records and photo libraries from sellers who genuinely thought they had cleaned up.
The good news: encryption changed everything
Modern phones and most recent computers encrypt their storage by default. That flips the problem: instead of needing to scrub every byte, the built-in factory reset simply destroys the encryption key, and everything on the drive becomes permanent gibberish in seconds. So on current devices, the official reset procedure really is enough – the trick is doing the steps in the right order, and knowing the exceptions for older hardware.
Before any wipe: the 15-minute pre-flight
- Back up anything you want to keep – see the 3-2-1 rule.
- Sign out of accounts: especially iCloud/Find My on Apple devices and your Google account on Android. Skipping this triggers activation locks that make the device useless to the buyer, and unlocking remotely later is a headache.
- Deauthorise licensed software (music apps, creative suites) that limits how many machines can use your licence.
- Remove SIM and memory cards – a surprising number of “wiped” phones ship with the previous owner’s SD card full of photos.
iPhone and iPad
Settings → General → Transfer or Reset → Erase All Content and Settings. The process signs you out of iCloud, disables Activation Lock and destroys the encryption key. iPhones have been encrypted by default for over a decade, so this genuinely is the whole job.
Android
First remove your Google account (Settings → Accounts), then factory reset (Settings → System → Reset options). Android devices from roughly 2015 onward are encrypted by default; if yours is very old, encrypt it manually in security settings before resetting, which achieves the same key-destruction effect.
Windows PCs
Settings → System → Recovery → Reset this PC → Remove everything, and when asked, choose the option to clean the drive / remove files from all drives. That last choice is the one that matters – the quick version only deletes, the clean version makes recovery impractical. If the machine used BitLocker encryption (check under Settings → Privacy & security → Device encryption), the reset destroys the key and the job is thorough by design.
Macs
On any reasonably recent Mac: System Settings → General → Transfer or Reset → Erase All Content and Settings. Like the iPhone, this signs out of your Apple ID and destroys the FileVault encryption key. On older Macs without that feature, boot into recovery mode, use Disk Utility to erase the drive, and reinstall macOS.
The special case: old unencrypted drives
Selling an old external hard drive or a pre-encryption laptop? A plain format is not enough. Use a dedicated wiping tool that overwrites the disk (one full pass is sufficient on modern drives – the folklore about needing 35 passes is decades out of date). For SSDs, use the manufacturer’s “secure erase” utility instead of overwriting tools. And for a drive that is dead, failing, or held data you would genuinely lose sleep over: physical destruction is legitimate. Remove the drive, and a hammer through the platters or professional shredding settles the question for the cost of nothing.
Do not forget the devices that do not look like computers
Smart TVs store streaming logins. Printers can hold scanned document history. Routers store your Wi-Fi password and sometimes your ISP credentials. Game consoles hold payment methods. Cars – especially ones you sell – store paired-phone contact books and home addresses in the navigation. Each has a factory-reset option buried in its settings menu, and each is worth the two minutes before it leaves your house.
