You might feel the need to reinstall macOS Sierra, as if you just got your computer and boot it for the first time. However, in contrast to Windows, macOS doesn’t need to be “clean installed” after every update or after every new version of the system.
Still, I decided to reinstall the system for two reasons:
1) I have never cleaned up my system since I bought my Mac five years ago,
2) I’m planning to use this hard drive as a back up drive and use an SSD instead (tutorial will follow)
Watch how I cleaned my hard drive and reinstalled macOS Sierra below or read the written tutorial under it:
STEP BY STEP GUIDE
If you’re thinking of doing the same thing, please read the follow paragraph:
Before we begin:
- Make sure you have all the necessary backups of your files, as the following steps will ERASE YOUR HARD DRIVE!
- I am not responsible for any problems caused on your computer. These steps are the ones I followed and worked on my Mac. While normally, your Mac should do the same things, any unexpected abnormalities might cause problems for which I’m not responsible.
- Just in case, make sure you have a copy of macOS on a bootable dvd or usb drive so you can reinstall macOS without internet if needed.
This is what I did:
- I booted my Mac into Recovery Mode by holding CMD+R while booting.
- Clicked on Disk Utility.
- Chose my hard drive (NOT the Mac OS base file!) and clicked on Erase.
- A small window popped up:
– I chose a new name for my hard drive,
– selected Mac OS Extended (journaled),
– and left the GUID-partition table as it was.
- I clicked Erase and my hard drive got erased (relatively quickly).
- I quit Disk Utility when it was finished and it returned to the main screen of Recovery Mode.
- I clicked on Reinstall macOS Sierra.
- Pressed Continue.
- The setup verified if my computer was allowed to download macOS. (I was connected to WiFi.)
- I agreed with the terms in conditions, chose the hard drive onto macOS should be installed and let the setup do its thing. The whole installation took 20 minutes.
- When it was done, my computer rebooted and the setup continued. I followed the instructions (logged in with my Apple ID, enabled location services, etc.) .