How to create a macOS Catalina USB installer.

Factory reset MacBook Air and other Macs with macOS.

How to downgrade from macOS Mojave to macOS High Sierra.

Or use the OS X installation disc that came with your machine - or buy a new one - to boot up and install OS X on your Mac’s hard drive.

Download the relevant macOS or OS X installer from Apple, then use Terminal to create a USB installer you can boot up from.Install macOS or OS X from Internet Recovery Mode, which you can boot into by holding option+command+R while your Mac powers up.If you’re tech-savvy but don’t know where to start, use these Quick Tips to point you in the right direction for getting macOS or OS X on your drive: How do I install OS X on my hard drive using an installation disc?.How do I use a bootable USB installer to install macOS or OS X?.How do I create a bootable USB Installer?.Which version of macOS or OS X should I create an installer for?.Create a bootable USB installer for macOS or OS X.How do I use Internet Recovery Mode to install macOS or OS X on my hard drive?.Install macOS using Internet Recovery Mode.

How do I use Disk Utility to reformat my hard drive?.Format your new hard drive for macOS or OS X.

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