Apple calculator like iMac, Macbook Air, Macbook Pro or Mac Mini are popular - their resale value is correspondingly high. However, you shouldn't simply give the computer away as it is: Before selling, you should reset the computer professionally and remove all data - of course only after you have created a Time Machine backup. This is the only way you can be sure that all data has really disappeared from the system before the buyer puts it into operation.
Note: If you're using a Mac running MacOS 12 or later, you might be able to too the MacOS deletion assistant use.
Factory reset or just reset?
A pleasant side effect: The Mac then behaves as it did when it was delivered, the buyer only has to set it up. However, there are two variants: This guide describes how you can reset your Mac with the current operating system version. However, this is not always the same as the one with which the Mac was delivered: In order to really restore the Mac completely and including the operating system to the delivery state using Internet Recovery, you have to follow this tuto here follow. The steps are largely similar, but the variant described here is easier.
Caution: Be sure to turn off FileVault and Find My Mac before resetting! Otherwise it can happen that the Mac blocks and has to go to the workshop!
1. Call MacOS recovery system
Start the Mac and press the key combination CMD+R at the start-up sound to call up the rescue system on the recovery partition. This has been available since Mac OS X 10.7 "Lion". Users of older system versions must insert the CD/DVD that came with the Mac and press the C key instead of CMD+R to start the rescue system. Starts Disk Utility in the rescue system. Caution: It is recommended that you factory reset your Mac completely when you sell it.
2. Select system disk
In Disk Utility, click on your system disk and select the Erase tab. Depending on the MacOS version and the configuration of your system, you may have to select the system partition instead (“MacintoshHD” in the screenshot) if that doesn't work. The procedure is otherwise identical: Assign a name and click on "Delete". Repeat this with other partitions and internal hard drives if you use any.
If you really want to be sure that all data is gone, you must also select a secure deletion method under "Security Options", which only makes sense with conventional hard drives - the "Overwrite" options are not useful for SSDs. Unlike conventional hard drives, however, data on SSDs cannot be "saved" as easily. Therefore confirm the message with "Delete", then the hard disk will be deleted.
3. Quit Disk Utility
Now exit Disk Utility with the key combination CMD+Q or via the menu bar. You end up back in the rescue system start screen.
4. Reinstall Mac OS X
Now select “Reinstall OS X” and click on “Continue”. The OS X installation files are not on the rescue partition, but have to be downloaded from the Internet since OS X 10.7. You should therefore ensure that your computer is connected to the Internet via WLAN or network cable before you continue.
5. Start installation process
You are now in the start screen of the OS X installation. Click on "Continue", confirm the message about the verification at Apple with "Continue" and then nod the license agreement.
6. Sign in to the AppStore and start the installation
Now click on the system hard drive and select "Install". Your Mac will now ask for the access data for your Apple ID - this is only the verification process by Apple, so that you can download the operating system again from the App Store. Then click "Sign in" to start the installation and begin the macOS installation.
7. Download and install OS X
OS X will now download from the AppStore and then install, which may take a good while. Follow the on-screen instructions to continue the installation if necessary. However, the installation runs largely smoothly. The computer restarts once on the way between the download of the installation files and the actual installation.
8. Turn off Mac
Once the installation is complete, all you have to do is turn off the Mac. The operating system is already installed, but not set up, after all the new owner should also do that. In this respect, you can switch off the computer, pack it up and send it off as soon as you see the OS X intro.
Factory reset Mac & sell it
By the way: If there are problems with the Apple ID because you bought the Mac used, this tip may help you. Alternatively, you can use your Mac, if it already has the corresponding function, reset to factory settings and thus to the original operating system via Internet recovery – ideal if these instructions no longer work because your Mac is too old. And if you want to know where you can sell the device most lucratively, we've got you covered here are some tips for your convenience.