What should I do to reclaim space by removing an unneeded Bootcamp partition?

Download the desired macOS, make a bootable USB installer from it, Option boot to it, switch to Disk Utility > View > Show All Devices and select the topmost device and erase it as APFS (case insensitive), switch to macOS installer and install.

How to download and install macOS - Apple Support

Create a bootable installer for macOS - Apple Support

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

➡️ This will even remove the BootCamp Partition ⬅️

>> Only works on Intel Based Apple Computer <<

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

The Bootable Installer can Only be performed on an Apple Computer 

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 Ventura would have to be done on a computer that Qualifies to run Ventura.

Notation: If the computer being used to perform this action is Too New or Too Old to qualify to run the version of macOS - this computer can’t be used.

Alternative is, to gain access to a Qualifying Apple Computer from a family member, friend or associate.

Extra Special Notation regarding the Touch ID equipped Apple Computer.

And Yes, according to Apple this computer Does Contain the Apple T2 Security Chip

 About Startup Security Utility and Must Enable from Recovery Mode the ability to boot from External Drive Before Attempting 

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

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

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

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

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. 

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

Follow the prompts and it may automatically reboot several time. 

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

You can use Setup Asset and point it to the Time Machine Backup Drive. This is a One Time offer. Thereafter you will need to use Migration Assist 

VikingOSX wrote:

The only way to remove a Bootcamp partition is with Bootcamp which will rebuild the partition map and release that storage back to the drive. If you remove that partition by any other means short of erasing the entire drive, you will not rebuild the partition map, and that 74 GB will be unavailable to you as lost storage.

I have never really used BootCamp but I have been under impression that the BootCamp app was just a smoother workflow that could also be accomplished via DiskUtility, Terminal etc if the user knew what he was doing.

So did I understand correctly that only BootCamp can revert the partitions it has done for Windows? And the other alternative to regain that disk space is to erase the whole device with DiskUtility? Or are there DiskUtility GUI or CLI tricks also available to revert BootCamp partitions and regain disk space?

Matti Haveri wrote:

VikingOSX wrote:

The only way to remove a Bootcamp partition is with Bootcamp which will rebuild the partition map and release that storage back to the drive. If you remove that partition by any other means short of erasing the entire drive, you will not rebuild the partition map, and that 74 GB will be unavailable to you as lost storage.

I have never really used BootCamp but I have been under impression that the BootCamp app was just a smoother workflow that could also be accomplished via DiskUtility, Terminal etc if the user knew what he was doing.

So did I understand correctly that only BootCamp can revert the partitions it has done for Windows? And the other alternative to regain that disk space is to erase the whole device with DiskUtility? Or are there DiskUtility GUI or CLI tricks also available to revert BootCamp partitions and regain disk space?

Boot Camp creates a partition on which Windows is installed. To remove the created partition you must use Boot Camp Assistant to remove Windows and the partition. You can not use Disk Utility to remove and reclaim a Boot Camp created partition.

The only way to remove a Bootcamp partition is with Bootcamp which will rebuild the partition map and release that storage back to the drive. If you remove that partition by any other means short of erasing the entire drive, you will not rebuild the partition map, and that 74 GB will be unavailable to you as lost storage.

Click the back button and skip signing into your AppleID & iCloud. This has been an issue for several years now. After completing setup, then you can sign into your AppleID.

FYI, macOS defaults to enabling all options for iCloud, so if you don't want stuff syncing to iCloud, then make sure to check out the iCloud settings in the System Settings app & configure them as you prefer.

You can try providing Apple with product feedback here:

Product Feedback - Apple

lanstrad1 wrote:

• Two problems.... after erasing everything:

An error occured installing the update . Try again or select startup disk.

• If I try again, of course it does not work

• If I select Startup Disk, I am being told that security settings do not allow this mac do be started from an external disk !!

That is correct, it would Not Boot from the USB drive called " Install Sonoma "

Open Startup Security Utility

1. Turn on your Mac, then press and hold Command (⌘)-R immediately after you see the Apple logo. Your Mac starts up from macOS Recovery.
2. When you're asked to select a user you know the password for, select the user, click Next, then enter their administrator password. 
3. When you see the macOS utilities window, choose Utilities > Startup Security Utility from the menu bar.
4. When you're asked to authenticate, click Enter macOS Password, then choose an administrator account and enter its password.

As previously mentioned this computer has a T2 Chip, Would Require changing the Setting to " Allow booting from external or removable media "

Matti Haveri wrote:

I have never really used BootCamp but I have been under impression that the BootCamp app was just a smoother workflow that could also be accomplished via DiskUtility, Terminal etc if the user knew what he was doing.

Theoretically, you are correct. However, there are lots of posts on this forum where people are unable to use Disk Utility to re-merge the Bootcamp partition back into the main OS partition/Container. The Disk Utility GUI app is not very good at its job.

So did I understand correctly that only BootCamp can revert the partitions it has done for Windows? And the other alternative to regain that disk space is to erase the whole device with DiskUtility? Or are there DiskUtility GUI or CLI tricks also available to revert BootCamp partitions and regain disk space?

It is possible to use the command line utility "diskutil" to re-merge the partition, but I am not fully certain on the exact option to use to do it. Once I posted a suggestion, but I was slightly off on the option. The OP at the time was able to look at the "diskutil" options to figure out the proper options to use, but I don't recall those specific options (it was several years ago). The trouble with the command line is the person must be able to figure out the correct drive identifier to use since the drive identifiers can change with every boot, especially if other devices are connected which makes it very difficult to assist users.

• With the OPTION button, I am presented with :

• Install macOS Sonoma.

There is no option for the USB stick.

"Install macOS Sonoma" is the USB stick.