The old hard drive from my Mac is destined to find a new role in my low-power server (hopefully dropping the power consumption even further by switching from a 3.5″ disk to a 2.5″ disk). Before that can happen though, I needed to wipe it and clone my Windows Server installation.

After hooking the drive up, I found that it had two partitions: one large non-Windows partition that was easily removed in Server Manager’s Disk Management snap-in; and one EFI partition that Disk Management didn’t want to delete.

The answer, it seems, is to dive into the command line and use diskpart.exe.

After selecting the appropriate disk, the clean command quickly removed the offending partition. I then initialised it in Disk Management, electing to make it an MBR disk (it was GPT).