You'll start by holding down left Shift + F10 to open a Command Prompt, then enter PowerShell. Once PowerShell is started, run New-OSDDiskWinPE
The first prompt is a Warning that you will lose everything on the Hard Drive if you keep going ... Press Enter to continue
Now here is the prompt where Clear-Disk will destroy your data. Press Enter, or Y then Enter
Now you are prompted before the Partitions are created. Enter the number of the Disk, which is 0 and press Enter (or just press Enter since nothing = 0)
Now the Partitions are perfect