In this article, we’re going to show you how to perform a clean install of macOS, but before we get in to how to wipe your Mac and reinstall macOS we will discuss the difference between a clean install and a plain reinstall of macOS, and why you might want to do a clean install of macOS. Is a clean install better than a reinstall, or is it actually completely unnecessary to wipe your Mac first?
We will then discuss the different ways to do a clean installation of macOS. Traditionally, the way was to make a bootable copy of the macOS installer on a USB stick and then reformat your drive before installing the bootable copy onto your Mac, however, this is unnecessary for modern Macs. There is now a simple method to wipe a Mac and it is possible to use macOS Recovery to reinstall the Mac operating system over the web (we have a separate tutorial about how to reinstall macOS using Recovery).
Read more at Macworld.com