Wiping a Mac is simple. Losing fifteen years of photos on your Mac in ninety seconds happens when you wipe the computer in the wrong order. Here's the correct sequence to follow: get all files backed up or copied from the computer, check that the backed up files are what they are supposed to be, sign out of everything, then delete everything. None of these steps are optional and deleting is permanent, which is the whole reason the first three come before it.
You will need to get all of your data off the old Mac properly. Copy your files to an external hard drive, copy them to iCloud, or use Migration Assistant to move them to the new computer. Once you have done this, open some of your files. The fact that a folder has been copied with no errors does not mean that the contents of the folder can be opened. Look at your photos. Can they render? Do your documents open? Did both Desktop and Downloads come over? (These are often missed.) Sign out of iCloud. Turn off Find My. Sign out of iMessage. And (most people forget about this) deauthorise your Mac in Apple Music if you ever used iTunes on the old Mac. Unpair any items that were paired via Bluetooth so that when the new owner gets their computer, they don't have your keyboard.
Any Mac that has an Apple Silicon processor (or has a T2 chip), so basically every new model from 2018 onward, will have only one correct way to erase the drive. That is not using Disk Utility. Open System Settings and go to General, then choose Transfer or Reset. The option you need is called Erase All Content and Settings. It works in exactly the same way that its iPhone equivalent does: it removes you from your account, deletes your data and returns your Mac to factory settings, with the setup assistant ready for use.
What this actually does is important to understand as well because it will help you make sense of everything we covered in the last section. In all cases, regardless if FileVault has ever been turned on, the encryption used by flash memory within these computers is permanent and done at the hardware level. When "Erase All Content and Settings" is selected it deletes the encryption keys. Although the actual physical data (bits) stored on the flash remains there after selecting "Erase All Content and Settings," without the proper decryption key those bits represent meaningless random noise and always will. This is why the erase operation takes a couple of minutes rather than an hour, and also why nothing will survive this operation. If you see the option greyed out, it may be because you are using an earlier version of macOS or you have not signed into your computer. Simply upgrade macOS, then sign in to your account; at that point, the option should appear.
Pre-2018 Intel-based Macs with no T2 have no one-button method, so it has to be done by hand. Shut down. Pressing Command and R while booting will take your Mac into macOS Recovery. In Recovery mode, open Disk Utility. Select View > Show All Devices in order to view your physical disk instead of only its volumes. Select the top level device. Click "Erase". The format should be APFS if the hardware is reasonably modern; otherwise use Mac OS Extended (Journaled), and in either case use GUID Partition Map as the scheme. Quit Disk Utility, then reinstall macOS via the Recovery menu.
On those systems, FileVault really does matter as your files are not encrypted out of the box. With FileVault on when you wipe the system, you destroy the key to unlock them. Without it enabled, wiping will leave behind recoverable fragments (on a hard disk) or may be very difficult to recover if the data has been trimmed from an SSD. Want to sell an older Intel MacBook with a spinning drive and no FileVault? Enable FileVault, allow it to complete its encryption and then perform a wipe. Ten minutes of patience closes the gap entirely.
Thorough. Once the keys are gone on an up-to-date Mac computer, all of your information is gone as well, and there is simply no laboratory in the world that can recover any information from that computer (including this one). The fact is, there isn't a single method to recover information from a properly wiped Apple Silicon or T2 based machine, and anyone telling you they have such abilities is attempting to sell you something. This is a good design and the right one for computers that change ownership.
The corollary usually gets people because a modern Mac's flash is now soldered directly to the logic board (and locked to that board's encryption) and can't be removed from the logic board so as to read its data somewhere else. This bench can't take storage soldered onto a motherboard of any computer, which means that the backup you did before wiping is not a precaution, it is the only backup: test that the backup opens before you hit the button, not after.
A large number of the Macs coming in here had their hard drive erased unintentionally. Either the machine failed (the machine died) and someone attempted to start it again via a reset; or a student from Aberdeen or Robert Gordon University reinstalled the operating system to solve a boot loop problem with a dissertation still on the original disk; or a user initiated a "reset" but the battery went flat before completion. Interrupted erases are the recoverable ones, as the process is often not as complete as the progress bar suggested.
We follow the standard rules. On an older Mac whose drive or SSD blade unscrews, the storage comes out and is read on its own, regardless of the cause of death of the machine; this generally equates to an easy recovery. On a 2018-or-later model the flash is soldered down to the board and fully encrypted to it. We do not take this type of system and would rather tell you over the phone than after you have paid for postage. If the computer is an earlier model (with removable storage), there is no cost associated with our diagnostics, they complete within 2 working days once received, and you will receive a single fixed written price prior to any work beginning. Call us at 0800 689 0668 and answering one question will identify the machine.
Files off first, wipe second: the sequence of events still matters. Both routes are irreversible, and once you have destroyed the keys inside the soldered, encrypted flash in your modern Mac, nothing will restore that data. Copy the file(s) you wish to protect. Open what you just copied. Verify that everything has been transferred correctly. Only after you've confirmed this can you press the button.
The diagnosis is free and takes 2 working days once your disk arrives at our premises. The figure quoted is fixed and given to you in writing, and on logical work, in most cases you only pay if we recover your data. Begin online today or call us.