• Looking to free up space on my MBP - there is a "Install macOS High Sierra.app" 5.2GB - can I delete this? Should I save it onto an external backup in case it isn't easily downloadable in future and I need to reinstall the OS?

  • my instinct is that you can definitely delete that.
    Should you need to re-install in the future, you can start the download off again from the recovery drive/bootup menu.

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