Clean partition map before installing High Sierra I'm about to do a clean install of High Sierra on my iMac and I have a Bootcamp partition with Windows 10.

I've checked the partition map, there are a lot of partitions I don't know about and I would like to delete all the unnecesaty ones.

Here is my diskutil list result.
disk0 is your physical internal disk.


disk1s1 is required by macOS. Windows also stores boot software in this partition. 
disk1s2 is used by macOS. The partition is not used by Windows.
disk1s3 is used by macOS. The partition is not used by Windows.
disk1s4 is used by Windows. The partition is not used by macOS.
disk1s5 is used by Windows. The partition is not used by macOS.


disk1 is virtual and exists because you are using core storage. 

disk2 is the USB macOS installer.

The rest of the disks and partitions only exist because you are booted to the macOS installer. You should not try to delete these partitions.

Basically, the installer creates virtual disks in your computer's volitile RAM memory. These disks are used for temporary file storage. For example, compressed files stored on the USB drive are decompressed and stored on these disks.

You should be able to delete disk0s2 and disk0s3 without affecting Windows. If for some reason Windows will not boot, then you will need to create a bootable USB Windows Installer to fix the problem. If necessary, you can do this from macOS. I would avoid deleting the macOS volume. Instead I would do the following.


Boot to the USB macOS installer.
Open the Disk Utility application.
Erase the macOS volume using the format "Mac OS Extended (Journaled)". This  should:


Remove Core Storage  on partition disk0s2.
Remove the "Recovery HD" volume on partition disk0s3.
Create a  "Mac OS Extended (Journaled)" volume on a new partition.

Exit the Disk Utility application.
Restart and boot back to the USB macOS installer.
Install High Sierra on to the new volume. This should also create a new "Recovery HD" volume.