Can't delete an old Boot Camp partition after formatting it in Disk Utility

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Level 1

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Can't delete an old Boot Camp partition after formatting it in Disk Utility

Hi there

I'm trying to format my 2011 iMac's hard drive to be just one partition, as I plan to sell it soon. It used to have a 100 GB Boot Camp installation on it. I didn't realise that to remove a Boot Camp partition, you are supposed to use the Boot Camp Assistant and instead tried erasing it using Disk Utility while reinstalling macOS (High Sierra).

The problem is, now I'm stuck with two "Macintosh HD"s, one 888 GB (the main partition) and one 100 GB (the erased Boot Camp partition). Erasing the partition in Disk Utility within macOS doesn't get rid of it. It just seems to reformat it. Restoring the partition doesn't work and gives me "OSStatus error 19".

I've tried searching for a solution but just can't seem to work it out. I hope someone can help.

Cheers,

Tom

iMac 27″, macOS 10.13

Posted on Jan 10, 2021 7:05 PM

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Answer 1

Best reply

K Shaffer

Level 7

34,984 points

Jan 11, 2021 1:01 PM in response to Tirvy

You still need to Erase the entire storage drive and Reformat to regain lost capacity.

• Erase a volume using Disk Utility on Mac - Apple Support

https://support.apple.com/guide/disk-utility/erase-a-volume-dskutl14079/18.0/mac/10.14

Erasing a Disk deletes everything on it. Erasing a Volume deletes all

the files on that volume, but does not affect other volumes.

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Answer 2

Tirvy Author

Level 1

8 points

Jan 11, 2021 12:18 PM in response to BDAqua

Thanks, I gave that a shot. Unfortunately, when I tried erasing the whole drive it failed stating that it couldn't unmount the disk. I named it Macintosh HD, set "Format" to Mac OS Extended (Journaled) and scheme to GUID Partition Map. When I tried partitioning it with one partition selected, it gave the same explanation about not being able to unmount the disk.

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Answer 3

BDAqua

Level 10

239,327 points

Jan 11, 2021 6:23 AM in response to Tirvy

In Disk Utility in Recovery Mode, be sure to use the View Menu to Show all devices, then highlight the top, (whole Drive), to format it.

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Answer 4

BDAqua

Level 10

239,327 points

Jan 11, 2021 1:05 PM in response to Tirvy

Hmm, and this was in Recovery mode???

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Answer 5

Tirvy Author

Level 1

8 points

Jan 11, 2021 1:27 PM in response to K Shaffer

Hey, thanks for the response. Unfortunately I've already tried this both in macOS and in recovery mode and it failed stating that it couldn't unmount the disk.

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Answer 6

Tirvy Author

Level 1

8 points

Jan 11, 2021 1:28 PM in response to BDAqua

Yep, definitely in recovery mode.

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Can't delete an old Boot Camp partition after formatting it in Disk Utility

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