Disk utility erase feature - Catalina - not sure which is HD

Hi - I'm trying to to do a factory reset on an iMac (Catalina), so I can give it to my partner to use (will reinstall using his Time Machine backup). I've got as far as disk utility but can't identify the HD. It's a refurbished Mac so may have a different HD. I've attached photos of what's shown (Volumes and Devices). If anyone can tell me which one to select and erase that would be great. Thanks

iMac 27″, macOS 13.7

Posted on Nov 9, 2025 2:44 AM

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Posted on Nov 9, 2025 3:36 AM

For reference: What to do before you sell, give away, trade in, or recycle your Mac - Apple Support. Follow all those steps first. If you don't do that prior to erasing the Mac, it will be too late.


Then and only then following Step 6. Erase your Mac and reinstall macOS will describe what to do.


It's a refurbished Mac so may have a different HD.


Refurbished Macs are indistinguishable from new Macs. This assumes it was refurbished and sold to you directly from Apple and not some third party, who often irresponsibly and fraudulently claim it was "refurbished" when it was not.

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Question marked as Top-ranking reply

Nov 9, 2025 3:36 AM in response to VickyLB

For reference: What to do before you sell, give away, trade in, or recycle your Mac - Apple Support. Follow all those steps first. If you don't do that prior to erasing the Mac, it will be too late.


Then and only then following Step 6. Erase your Mac and reinstall macOS will describe what to do.


It's a refurbished Mac so may have a different HD.


Refurbished Macs are indistinguishable from new Macs. This assumes it was refurbished and sold to you directly from Apple and not some third party, who often irresponsibly and fraudulently claim it was "refurbished" when it was not.

Nov 9, 2025 12:42 PM in response to VickyLB

VickyLB wrote:

It's a secondhand Mac, from TechTrade (not an Apple refurb) - and I requested the HDD upgrade.


I suspected it was purchased "used". In that case the Apple Support document may be difficult to follow.


The most conservative action would be to select macOS - Data. Select that then Erase.


By default Apple ships Macs with Macintosh HD as the startup disk name, as illustrated under Use the Erase feature of Disk Utility in Use Disk Utility to erase an Intel-based Mac - Apple Support. There is no technical reason you cannot change that name to anything you want; it just makes things difficult for yourself when trying to follow Apple Support documents such as that one.

Nov 9, 2025 5:03 PM in response to VickyLB

For an Intel Mac, you can select the whole physical drive to erase (don't do that with an M-series Mac), otherwise look at the Disk Utility erase options in the Apple article @John Galt linked....specifically the section "If You Cannot Use the Erase All Contents and Settings" option.


FYI, the physical drive is the top most item you have highlighted in the second picture...."WDC WD30EFAX-68....".

Nov 9, 2025 5:34 PM in response to VickyLB

Here man im a mac specialist. In the second image you uploaded thats the actual drive you have selected and thats the one you need to erase. Make sure when you click erase you select GUID and MacOS extended journeled. Macos And the drive macos Beta are just partitions macOS had made. They wont make a difference. Once you erase the whole disk restart the mac and hold command r and let internet recovery load. (As there is no recovery partition anymore it will default to internet recovery.) Then you can join your network and select reinstall macos in recovery, accept the license terms and slect the disk

Disk utility erase feature - Catalina - not sure which is HD

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