It turns out that the solution is very simple. To do that we need an installation disc with operating system. Personally, I use my disc with Windows 7. Boot from it, launch console when prompted to select partition. Use key combination <Shift+10> to launch it. Having done that you will see console. Now you need to launch a command-line hard disk partitioning utility called diskpart.
After you have launched it, run list disk to see the index list of your disks. Then run select disk # and select disk you are going to work with. Put your disk number in place of ‘#’. After you have selected the disk, all operation will be executed with it.
Then clean all the information from it by running clean command. After that you can proceed to conversion.
A convert mbr command will convert GPT disk into an ordinary one.
After that you can work with disk as usual and install any operating system you want.
Besides that, you can create partitions with the help of this utility.
create partition ptimary size=n – creates a new primary partition, size ‘n’ Megabytes.
format fs=ntfs label="System" quick – quickly formats selected partition into NTFS.
active – marks partition as active.