Cannot format my hdd

i just got my new laptop and it has endless os instaled.
i tried to instal windows 10, but I cant since my hdd partition type is linux roor partition.
so I tried to format my hdd and change it into ntfs but i got error umnounting filesystem mesage.

can someone help me?

It appears from the screen shot that you are trying to format you disk using Disks which is part of Endless. Disks will not let you unmount the partition that the operating system is using.

If you have a Windows installer for you machine you should be able to format the hard drive as part of the Windows installation process. For specific help on installing Windows you should refer to Microsoft’s help site.

bill