How to wipe a device before you sell or recycle it

Wiping a device means replacing or destroying the data rather than hiding it, and the order matters: back up, sign out, erase, then hand it over. CISA, the US cyber security agency, explains in its paper on disposing of devices safely that removing information takes more than the delete key, because recovery tools can bring deleted files back. cisa.gov

Why deleting is not erasing

A normal delete removes the pointer to a file, not the file itself. CISA describes three levels of removal, from least to most effective: deleting, overwriting, and physical destruction. NIST, the US standards body, defines clearing as a level of media sanitization that does not let information be recovered by data, disk or file recovery utilities, the standard a wipe tool should meet. csrc.nist.gov

Before you erase anything

Copy what you want to keep to a new device, an external drive or a cloud account, then open the copy to confirm it works. After that, cut the device loose from anything that can still reach it.

• Sign out of accounts such as the device maker's ID, email, cloud storage and password manager.
• Turn off anti-theft locks like Find My or activation locks, or the next owner cannot set the device up.
• Remove SIM and memory cards, which can hold contacts, messages and photos of their own.
• Unpair accessories such as watches, earbuds and car systems that still trust the device.

Phones and tablets

CISA sets out a simple sequence: remove the memory card if there is one, remove the SIM, then use the settings option named Master Reset, Wipe Memory, Erase All Content and Settings or something similar. Some devices ask for your passcode during the reset. Finish by confirming the account tied to the device is closed or moved to your new phone, and that the reset device shows its setup screen rather than your home screen.

Laptops, desktops and drives

On a computer, CISA recommends overwriting the drive, which means writing random data over the old contents, before resetting it to factory settings. Overwrite tools are widely available, but the agency warns against using them on solid-state drives, where the firmware spreads data across blocks; for those, use the secure erase option built into the drive or the maker's own utility. For a drive you no longer need at all, physical destruction is the most certain route.

Recycling the device itself

An erased device still needs the right disposal path. The US EPA advises deleting personal information, taking batteries out before recycling because they may need separate handling, and using a manufacturer, retailer or local scheme rather than household bins. Lithium-ion batteries in particular should not go into household rubbish or recycling. epa.gov

Bottom line: back up first, sign out of everything, erase with a tool that overwrites instead of deleting, then recycle through a proper channel. A few minutes of preparation stops an old gadget becoming someone else's way into your accounts.