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How to erase everything and do a clean install

I have a bootable monterey disc but I notice the hard drive is divided into an OS volume and a data volume. When I erase the disc in disc utility do I erase both? After that, I just boot to the thumb drive and install monterey? It's been a while since I did this. Thanks. (I plan to do this on two intel macs, a 2015 27" intel Imac and a 2019 Macbook Pro. Both are currently running Catalina).

iMac 27″, macOS 10.15

Posted on Sep 23, 2022 10:58 AM

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Question marked as Best reply

Posted on Sep 24, 2022 2:37 AM

" Scorched Earth Method "


This method will WIPE ALL Data and there is No Recovery - Period.


>> Only works on Intel Based Apple Computer <<


1 - Shutdown computer and disconnect all external drive Except the newly created Bootable Installer.


2- Restart and immediately hold the OPTION key until the Startup Manager appears and choose the USB Drive. 


3 - It will present options >> Disk Utilities >> View >> View ALL attached Drives. 


4 - Choose the Upper Most Drive ( not the volumes indented and list below ).


5 - The drive normally is called Apple Media or Apple SSD - that is the drive to Erase and format as APFS with the GUID Partition Map. This applies to macOS 10.14 Mojave and above


6 - Once that is done >> backup out of Disk Utilities and choose install macOS. 


7 - Follow the prompts and it may automatically reboot several time. 


8 - Upon a final reboot - Setup Assist will present with the newer version of macOS.

4 replies
Question marked as Best reply

Sep 24, 2022 2:37 AM in response to marby

" Scorched Earth Method "


This method will WIPE ALL Data and there is No Recovery - Period.


>> Only works on Intel Based Apple Computer <<


1 - Shutdown computer and disconnect all external drive Except the newly created Bootable Installer.


2- Restart and immediately hold the OPTION key until the Startup Manager appears and choose the USB Drive. 


3 - It will present options >> Disk Utilities >> View >> View ALL attached Drives. 


4 - Choose the Upper Most Drive ( not the volumes indented and list below ).


5 - The drive normally is called Apple Media or Apple SSD - that is the drive to Erase and format as APFS with the GUID Partition Map. This applies to macOS 10.14 Mojave and above


6 - Once that is done >> backup out of Disk Utilities and choose install macOS. 


7 - Follow the prompts and it may automatically reboot several time. 


8 - Upon a final reboot - Setup Assist will present with the newer version of macOS.

How to erase everything and do a clean install

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