Hit the Erase button, making sure that you fully understand the consequences and that all data will be erased. Make sure the Name of the HDD remains “Macintosh HD”, and that Format selected is “Mac OS Extended (Journaled)”.

Step 5: When Disk Utility is loaded, make sure that the main Mac hard drive is selected from the left hand side, and then click on Erase button. Make sure that you select Disk Utility from the available options and hit Continue to proceed to the next stage. Step 4: After the machine has finished making its checks and running its processes, a macOS Utilities menu will appear. Make sure that you select the plugged in bootable USB drive and hit Enter to continue. This will take you into an new menu, giving you the option of where to boot from. As the machine boots up, make sure that you keep the Option key pressed during the launch process. Step 3: With the USB bootable drive in our possession, we need to boot the Mac in question up from a cold start with the drive actually plugged in. You can follow the guide on how to make a bootable macOS High Sierra flash drive here: Make macOS High Sierra 10.13 Bootable USB Flash Drive Installer, Here’s How. This means that we don’t actually have to upgrade from another installation of something like Sierra or El Capitan, but rather lets us start afresh. When it has downloaded, we are going to use it to create our own bootable USB drive that allows us to fresh-install macOS High Sierra directly to our machines. Step 2: We mentioned above that we need the installer for our own purposes. When the installer has finished downloading, make sure that you quit out of the install as we want to use the install for our own purposes. If you haven’t downloaded a version of OS X/macOS previously, then the Mac App Store will initially download an installer and then try to walk you through the process of installation. Step 1: First up, download macOS High Sierra 10.13 final from the Mac App Store as it’s essentially the required part of the process. To find out if your Mac hardware is supported by this release, check here: macOS 10.13 High Sierra Compatibility: Full List Of Macs Compatible With Apple’s Latest Desktop OS. You’re obviously also going to need a Mac that supports the installation of macOS High Sierra.You can find how to backup your Mac with Time Machine in our post here (look under “Backup”). Important documents accumulate over time on our machines, so it would be disastrous to lose those through this installation. Make sure that all important data and any files or documents are backed up so that they aren’t lost in the process.

Clean install mac os sierra