I recently found this info useful from this link, when I was repurposing an old disk for a temporary and experimental installation of windows.
To manually wipe a drive and convert it to GPT:
- Turn off the PC, and put in the Windows installation DVD or USB key.
-
Boot the PC to the DVD or USB key in UEFI mode. For more info, see Boot to UEFI Mode or Legacy BIOS mode.
- From inside Windows Setup, press Shift+F10 to open a command prompt window.
- Open the diskpart tool:
diskpart
- Identify the drive to reformat:
list disk
- Select the drive, and reformat it:
select disk <disk number> clean convert gpt exit
- Close the command prompt window.
- Continue the Windows Setup installation.When choosing an installation type, select Custom. The drive will appear as a single area of unallocated space.Select the unallocated space and click Next. Windows begins the installation.