Convert GPT disk to MBR disk with EaseUS Partition Master
EaseUS Partition Master can directly convert GPT disk to MBR disk without any data loss (hard disk with system installed is not supported). You can also use EaseUS free partition software to solve other partitions cases such as to move gpt partition, partition gpt disk etc. Compared to Disk management and command prompt, it won't require to deleted disk volumes. Therefore, it is the safest and the most reliable way.
or convert gpt to mbr with Disk Management and Command Prompt
1. You must have administrator privilege to do this in Windows.
2. Before you convert a disk, be sure to backup anything on the GPT disk that you want to convert to MBR disk. Converting the disk requires that all partitions and volumes are deleted on the disk first.
Convert GPT disk to MBR disk with Windows Disk Management
1. Right click "My Computer" and choose "Manage" -> "Storage" -> "Disk Management".
2. Delete all volumes on the GPT hard disk which you want to convert to MBR disk. This action would cause data loss if there are important data in your disk volume.
3. Right click on the hard disk 1 and choose "Convert to MBR Disk". After you convert GPT disk to MBR disk, you can create partitions on the now MBR disk if you like.
Convert GPT disk to MBR disk via diskpart command
In the following case, I would like to convert disk 1 into MBR disk.
1. Input “DiskPart” at the search bar.
2. Type list disk and press enter.
3. Type select disk 1 and press enter.
4. Type detail disk and press enter. This will give you a list of all the volumes on the selected disk. If you do not have any volumes listed, then you can go to step 7.
5. Type select volume 5 and press enter.
6. Type delete volume and press enter.
Repeat steps 5 and 6 for each volume listed in step 4 until you have deleted all the volumes.
7. Type select disk 1 and press enter.
8. Type convert mbr and press enter.
diskpart command: convert GPT disk to MBR disk
9. Type exit and press enter.
I prefer Convert GPT Disk to MBR Disk with EaseUS Partition Master because it is easy to use.
Easeus partition site: http://www.partition-tool.com/