Performing a clean install macOS without a USB is fairly easy compared to other operating systems. I know traditionally most IT admins (IT Handy men) think about using a USB to quickly wipe and re-install a OS. But, some times there is NO USB available or the laptop does NOT have a USB port anymore or you might not have an adapter handy(This sucks!)

After brewing my own coffee at home and taking a walk around NYC and noticing so many red fire police call boxes I decided to put this brief tutorial together.

This is easy to do.

Before you start to Clean install macOS

Always! Always! backup, backup and backup your DATA. This process will erase all data. There’s NO going back.

Start the process

  1. Restart your mac or turn it OFF and the ON. While the mac is starting hold down Command + R keys.
  2. Release the keys when you see the Apple logo.
  3. You will see a “macOS Utilities” window. Select Disk Utility and Erase you main mac hard disk.
  4. Once the disk has been erased close Disk Utility window. You will be taken back to the “macOS Utilities” window.
  5. Now, connect your mac to the internet via Wifi or Ethernet cable(if possible).
  6. Select Reinstall macOS in the “macOS Utilities” window.
  7. Follow the instructions and make sure you select the HD you erased previously. This is the target drive macOS will boot from.
  8. The re-install process will begin. This may take some time due to your internet speed.

When done you will setup macOS as you normally do. Enjoy!

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