How to Create macOS High Sierra USB Installer Drive for Clean Install Here’s a complete step by step tutorial on how to create a macOS High Sierra USB installer drive right on your Mac for clean install. Learn to Create a macOS High Sierra USB Installer Disk for Clean Installation. If you are looking to clean install macOS High Sierra on your Mac, then having a USB installer disk is a must. In today’s guide, we will show you how to create one in a complete step by step fashion. But before we dive in, there are a couple of things you must do before you end up with a macOS High Sierra USB installer drive. Starting with downloading the macOS High Sierra image file from the Mac App Store. RELATED You Might Want to Install macOS High Sierra Right Away as Apple Patches a Number of Security Flaws, Inc Encryption & DoS Issues Download the macOS High Sierra Image File. If you don’t have the macOS High Sierra image file, then you have to download it first. You c...