Change a GPT Disk into an MBR Disk

Problem:

Some operating systems only support the older Master Boot Record (MBR) partition table, while newer operating systems support GUID Partition Tables (GPT). Sometimes it is necessary to install an older operating system on a disk formatted for GPT, which will not work unless the GPT disk is converted to MBR

Solution:

Convert the GPT disk into an MBR disk either by moving the disk to another computer and switching it over through the GUI, or from the command line via a recovery console or similar arrangement.

Procedure:

Ref: https://technet.microsoft.com/en-us/library/cc725797(v=ws.11).aspx

To change a GUID partition table disk into a master boot record disk using the Windows interface

Back up or move all volumes on the basic GUID partition table (GPT) disk you want to convert into a master boot record (MBR) disk.
If the disk contains any partitions or volumes, right-click any volumes on the disk and then click Delete Volume.
Right-click the GPT disk that you want to change into an MBR disk, and then click Convert to MBR disk.

To change a GUID partition table disk into a master boot record disk using command line

Back up or move all volumes on the basic GUID partition table (GPT) disk you want to convert into a master boot record (MBR) disk.
Open an elevated command prompt and type diskpart. If the disk does not contain any partitions or volumes, skip to step 6.
At the DISKPART prompt (right-click Command Prompt, and then click Run as Administrator), type list disk. Make note of the disk number you want to delete.
At the DISKPART prompt, type select disk <disknumber>.
At the DISKPART prompt, type clean.

Important

Running the clean command will delete all partitions or volumes on the disk.
At the DISKPART prompt, type convert mbr.

Important
Running the clean command will delete all partitions or volumes on the disk.

Value	Description
list disk	Displays a list of disks and information about them, such as their size, amount of available free space, whether the disk is a basic or dynamic disk, and whether the disk uses the master boot record (MBR) or GUID partition table (GPT) partition style. The disk marked with an asterisk (*) has focus.
select disk	Selects the specified disk, where disknumber is the disk number, and gives it focus.
clean	Removes all partitions or volumes from the disk with focus.
convert mbr	Converts an empty basic disk with the GUID Partition Table (GPT) partition style to a basic disk with the master boot record (MBR) partition style.

Limitations:

No known limitations.