Saving operating system when erasing iMac for trade-in or sale

[hakr100]

This is probably clear to many of you, but I have read Apple's directions a number of times and I am still confused. I am getting a new iMac next week and I need to remove my data from the old iMac. I'd like to sell it and I want to preserve the Catalina operating system on it. As far as I can tell from my limited understanding, it isn't clear what steps I have to take in the proper order to delete my personal data and third-party programs from the old iMac hard drive and yet preserve the OS. I know how to remove my info from the Cloud, et cetera, but exactly what do I have to do to accomplish what I want. I don't want to remove the OS and I certainly don't have a collection of DVDs with which to reinstall the OS. Advice, please. Thanks!

 

[mj_]

I find Apple's instructions on this to be very unambiguous : https://support.apple.com/en-us/HT201065
Particularly step 7: Erase your hard drive and reinstall macOS.

 

[hwojtek]

Catalina doesn't come on DVD.
1. Copy your whole computer to a portable HDD using Carbon Copy Cloner or SuperDuper.
2. Reboot to Recovery mode (hold alt and select "Recovery" or hold Cmd+R while powering up the computer)
3. Use Disk Utility from Recovery to erase your main drive
4. Reinstall MacOS to this drive using the built-in recovery installer.

 

[nambuccaheadsau]

If you had installed Catalina to an +8GB thumb drive, simply connect the thumb drive and choose it to boot from, erase the hard drive and install Catalina. When it wants to set up user information, click Command Q and the machine will shut down. When the new owner boots, screen will open at that point ready for th e new owner to proceed.

 

[deconstruct60]

This is probably clear to many of you, but I have read Apple's directions a number of times and I am still confused. .... I know how to remove my info from the Cloud, et cetera, but exactly what do I have to do to accomplish what I want. I don't want to remove the OS and I certainly don't have a collection of DVDs with which to reinstall the OS. Advice, please. Thanks!

You don’t have to remove anything from iCloud. the iCloud data isn’t stored on your computer . What you need to do is log out of Apple services that device is logged into . That is iCloud , Messages , FacesTime , etc etc. you should also logout of third party cloud services ( email , social media , entertainment apps , web browsers , etc . )

Apple does require removing the OS To reset things completely . However, you can download the OS from the Apple mothership in the recovery mode . It should grab the latest appropriate macOS version .

There are other recovery modes invoked by variations of the Key combos get different versions

How to reinstall macOS - Apple Support

You can use macOS Recovery, your computer's built-in recovery system, to reinstall the Mac operating system. Reinstalling macOS doesn't remove your personal data.

support.apple.com

The recovery mode bootstraps itself into a RAM images of itself , so it is possible to erase it from the drive it was launched from .

When reinstalling macOS on a now empty drive , you then stop at the ‘welcome to Macintosh‘ where select language . Unless, you need it run in some ‘demo’ mode for the buyer leave all the settings alone. ( can quit and or turn off system in that initial set up screen ) .

( if do need some sort of demo mode then have to find all the skip network , skip AppleID , skip anything personal options in the set up . Some of those are not immediately obvious ) .


when you do major macOS Installer downtown you can create a Bootable install drive

Create a bootable installer for macOS - Apple Support

You can use a USB flash drive or other secondary volume as a startup disk from which to install the Mac operating system. These steps are primarily for system administrators and other experienced users.

support.apple.com

( over time as the install drives have more ancient versions Apple may drop the signature authorizations on those . The up to date grap from Apple is safe , if not a big bandwidth bloat . the install drive can save bandwidth though for reasonable time periods . )