Reinstall macOS Sierra in iMac

Sdahe

macrumors 68000
Original poster
Oct 26, 2007
1,678
17
San Juan, PR
Hello,

I'm going to sell my imac and would like to know how to reinstall the OS so all my information is out of the computer.. how can I reinstall a fresh copy of macOS Sierra.

My current version is 10.12.6

Thanks
 

kohlson

macrumors 68000
Apr 23, 2010
1,994
539
You should be able to reboot into recovery mode. Immediately on hearing the gong: Option-R. Disk Utilities will be an option once booted, and erase disk is one of the options here. Then, choose the reinstall option in Recovery Mode. It's pretty straightforward once you boot into Recovery.

A more secure option is to enable FileVault first. You can do this before going into recovery. It can take several hours.
 

Fishrrman

macrumors P6
Feb 20, 2009
17,194
5,543
1. Download a copy of the Sierra installer. DON'T run it yet.

2. Use a USB flash drive 16gb (or larger) and ONE of the following:
- Boot Buddy
- DiskMaker X
- Install Disk Creator
...to create bootable USB flash drive with the installer on it, but... DON'T run it yet.

3. While still booted up in your current account, use Filevault to encrypt the entire drive (if you haven't done that already). This may take a little time, as mentioned above. When the drive has been encrypted, shut it down for the last time (you are about to erase it).

4. Boot from the USB flash drive installer.

5. Go to Disk Utility FIRST, and erase the internal drive. Set it up for HFS+ with journaling enabled. Do this, and your prior data will be unrecoverable (IF you used Filevault on the drive first)

6. NOW start the installer and do a fresh install. When done, it should boot to the "brand new Mac" screen, asking you to begin setup. At this point, I would just "pull the plug" and let it go dark. Leave it to the new owner to proceed from here.
 

Sdahe

macrumors 68000
Original poster
Oct 26, 2007
1,678
17
San Juan, PR
Yes it would. Only thing I would add is, do a secure erase instead of a normal one if you're concerned about the next owner being able to recover anything off the drive. This takes significantly longer as it has to write 0's to the entire drive.
Do I get that option in the same process?