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