This article explains how to erase and factory reset your Mac if you plan to give it away, sell it, or trade it in. Apple silicon Macs and Intel Macs with a T2 security chip (2017-2020 models) have an “Erase All Content and Settings” option available in macOS Monterey and later. If you have an older pre-2017 Mac, it’s a more convoluted process – follow this link instead to erase and factory reset your machine.
Traditionally, wiping a Mac and returning it to factory settings involved manually signing out of a range of services, erasing your Mac’s internal drive, then reinstalling macOS. These steps are quite involved when you consider how easy it is to wipe an iPhone or iPad (Settings -> General -> Transfer or Reset iPhone -> Erase All Content and Settings).
Fortunately, Apple includes the same option on newer Macs running macOS Monterey and later. Erase All Content and Settings in macOS offers a very simple and straightforward way to erase your Mac without needing to reinstall the operating system. Thanks to the way storage is encrypted on Macs with Apple silicon or the T2 chip, the option is able to instantly and securely “erase” all user date by destroying the encryption keys.
Read more at MacRumors.com