If you want to make a bootable USB for macOS, you will need to download the installation package from the Apple App Store.
Make sure your bootable USB flash drive is erased and formatted.
- Open Disk Utility found in the Utilities folder, select the USB flash drive in the sidebar, click the “Erase” button, and then format it.
- Name the USB flash drive to “Untitled” if it isn’t already assigned.
After its erased and formatted you will need to launch the Terminal application found in the Utilities folder.
Once it’s started Copy and Paste the following into the Terminal application:
sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled/ --applicationpath /Applications/Install\ macOS\ Sierra.app --nointeraction
Let the installer files copy and complete. Once finished reboot and boot off the USB to start the installation.
Friday, September 23, 2016
You can boot off the USB flash drive by rebooting your Mac and pressing Option ⌥ key.
For more information on Apple start up commands: https://support.apple.com/en-us/HT201255