Can’t Delete Disk Image

To perform this action will require booting from a Bootable Installer. 

This will have to be performed from a Qualifying Computer to run the version of macOS to be made on the Bootable Installer. Example : Bootable Installer of Big Sur would have to be done on a computer that Qualifies to run Big Sur.

Once that is done read on for preparing the Destination computer  >>

Only works on Intel Based Apple Computers.

Extra Special Notation regarding the Touch ID equipped Apple Computer. About Startup Security Utility and Must Enable from Recovery Mode the ability to boot from External Drive Before Attempting 

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. 

5A - Formatting for macOS 10.13 High Sierra and below requires HFS Journaled with the GUID Portion Map.

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.

What happens when you select the top item "ST500LM021-1KJ1..." and try to erase it? As long as the "AV" volume is not mounted, then erasing the physical drive (in this case "ST500LM021-1KJ1...") should work if you are booted into a macOS installer.

Edit: You must "erase" the physical drive, not delete it. Also the "OSX Base System" is the macOS installer. You cannot make any modifications to "OS X Base System" or the "Apple Disk Image...." items. Just ignore them as they are irrelevant for your purposes in erasing the internal drive.

Highlight the top ST200*** & erase the whole drive, nit sure but OS X Base System may reside in Firmware.

AV1234567890 Said:

"Can’t Delete Disk Image"

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Try Remounting the Drive:

Boot into Recovery Mode. (Silicon Chip or Intel Clip): Then, using Disk Utility, see if the Hard Drive shows Unmount. If so, then click the Unmount button, and then the Mount button. Then, try this once more.