How to Clean MacOS Sequoia
A clean install of macOS Sequoia installs the operating system on a freshly uninstalled Mac, removing all existing data, settings, and previous versions of macOS from the Mac. This method is sometimes chosen by advanced users who want a completely fresh start, who are solving persistent system problems, or who just want to use macOS Sequoia without the files left over from the previous installation. Also, if you don’t mind starting from scratch with no files, apps, or data, you can even use a clean install of macOS Sequoia as a way to downgrade a Mac from macOS Tahoe.
The method we will use here to perform a clean installation of MacOS Sequoia is to use a bootable USB installer drive, specially designed for the latest version of the MacOS Sequoia installer. After booting the Mac from the installer disc, you can erase the Mac’s internal drive, then install MacOS Sequoia on the freshly formatted disc, giving you a fresh installation when you’re done.
Before proceeding, remember that a clean install completely removes the Mac, meaning all applications, photos, files, media, backups, the operating system – literally everything. If you have important files or data, be sure to create a full backup first, either manually or using Time Machine or your backup method of choice.
macOS Sequoia Clean Installation Requirements
Before starting the clean installation process, you will need the following:
If you haven’t created a bootable installation drive, you’ll need to download the macOS Sequoia installer and create a USB installer first. If you already have a bootable Sequoia installer, you can skip this next section.
Create a macOS Sequoia USB Boot Installer Disk
Before starting, you will need a USB drive with at least 16GB of storage. Remember that the USB drive will be completely erased during this process.
- Download the latest version of the macOS Sequoia installer file (or use this direct download link for 15.7.4)
- Connect the USB drive to the Mac
- Open the Terminal application from the /Applications/Utilities folder
- Run the following command in Terminal, changing “MyUSB” to the name of your USB drive:
- Click Return and enter the administrator password
sudo /Applications/Install macOS Sequoia.app/Contents/Resources/createinstallmedia --volume /Volumes/MyUSB
The macOS Sequoia installer process usually takes a few minutes, depending on drive speed.
When the command finishes, the USB drive will be renamed to “Install macOS Sequoia”, and it will be ready to use as a bootable installer disk.
How to Clean Install macOS Sequoia via USB installer
A clean install involves booting the Mac from the installer drive, erasing the internal disk, and then installing macOS. Restart the Mac and follow the appropriate steps below, depending on whether you have an Apple Silicon Mac, or an Intel Mac.
- Connect the macOS Sequoia USB installer drive to the Mac
- Restart the Mac
- Quickly press and hold the Power button until the boot options screen appears
- Immediately hold the Option (⌥) key during startup
- When the boot menu appears, select the macOS Sequoia installer drive
- Select Disk Utility from the macOS Utilities screen
- Select the internal drive that currently contains macOS
- Click on Erase – Remember that this permanently deletes all data from the Mac
- Select Apple File System (APFS) as the format
- Click Erase to format the disk
- When the disk has finished erasing, exit Disk Utility to return to the main installer screen
- Now select “Install MacOS Sequoia” on the Utilities screen
- Click Continue and follow the on-screen instructions
- Select the newly removed internal drive as the installation location
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For Apple Silicon Macs:
For Intel Macs:
The Mac will start installing macOS Sequoia. This process may take a while, and the Mac may restart several times during the installation. Once complete, the Mac will boot into a fresh installation of macOS Sequoia.
If you happen to have a Time Machine backup available that is compatible with MacOS Sequoia, you will be able to restore your data from that Sequoia-compatible backup if you wish. You can use backups from older versions of macOS than Sequoia, but not newer ones (meaning Tahoe backups won’t restore to Sequoia). If you’re not restoring from a backup, you can just set up macOS Sequoia as if it were a new Mac.
Clean installing macOS can be useful when solving stubborn system problems, preparing a Mac for a new user or owner, starting fresh with a different version of macOS, or as a way to downgrade if you are not happy with a new version of macOS like macOS Tahoe.
Did you do a clean install of macOS Sequoia? Did you use a USB installer drive or another method? Share your experience with the clean install process in the comments.
