These are two answers I got directly from Apple after emailing Tim Cook yesterday
We are clearly lacking some documentation (and probably a feature in Disk Utility). However, you can achieve the removal using Boot Camp assistant.
Launch Boot Camp Assistant
Click the Continue button
You should now see a “Restore Disk to a Single Partition” screen.
Click Restore, enter password
Your system will now remove the windows partition.
Sorry our experience didn’t meet your expectations. I’ll work with my engineering teams and AppleCare to get this addressed.
You tube link
Getting rid of Boot Camp is super simple, you use boot camp assistant to remove what it may have created. There’s a handy YouTube video which explains this process here:
I’m interested in why the install failed, so before you do this if you can help us by collecting some information, great. If you don’t have time for, that’s cool too.
Using the Boot Camp Assistant to to remove the BootCamp partition:
- Start the Boot Camp Assistant from the Utilities folder.
- At the Boot Camp Assistant Welcome Screen click Next.
- If the Boot Camp Assistant cannot remove the partition it will error here. If it can then you will get another dialog asking you to restore the drive (i.e. remove the Boot Camp partition).
How to create Sysdiagnose logs:
- Launch Terminal from the Utilities folder in Applications.
- Type: “sudo sysdiagnose” and hit the “return” button
- Type in your password (for sudo)
- It will prompt you to press ‘Enter’ to continue. Press the return button to continue.
Once the logs have been gathered they will be compressed into a .gz file and created in the /tmp location. A finder window will pop up also once the file is created with the correct location. We need that file as well.
Sometimes the Boot Camp Assistant fails on the first install, we are looking into this issue, if you see a failure we’ve seen reports that attempting a second install will be successful.
I have removed the Apple employee names, in line with GDPR. I hope this helps people