To wipe and convert the drive by using Windows Setup

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.

When choosing an installation type, select Custom.

On the Where do you want to install Windows? screen, select each of the partitions on the drive, and select Delete. The drive will show a single area of unallocated space.

Select the unallocated space and click Next. Windows detects that the PC was booted into UEFI mode, and reformats the drive using the GPT drive format, and begins the installation.

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 0     —- 0 is the disk you want to format
clean
convert gpt       ( convert mbr if you want to bmr format)

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.