Open a command prompt and enter DiskPart to enter the DiskPart prompt. Win7/vista users can open the DiskPart prompt by entering DiskPart return directly in the search box in the Start menu.
At the DiskPart prompt, enter list volume to list all volumes, use select volume to move the focus to the corresponding volume on the hard disk, such as: Select Volume g (g is a drive letter on the hard disk), and then execute the delete volume to move the current The selected volume is deleted, the volume is repeatedly selected and the volume is deleted until all volumes on the hard disk are deleted.
After all the volumes on the hard disk are deleted, use list disk to list all the disks in the computer, and then use the Select Disk command to select the hard disk and finally execute convert GPT.
Converting a hard disk from MBR to GPT under windows