From dual boot Ubuntu with Windows 10 to clean Windows 10

Thanks to Ivan Jenic for the article which served as base for solving the problem. I've used two computers for this operation (the "broken" one and an healthy one with W10) and one 16GB USB (could have been 8GB too).

In the healthy computer,

1. Download the Media Creation Tool.

2. Connect the USB.

3. Run the Media Creation Tool with the desired settings on the USB.

It took me 32 min for "Download Windows 10" progress to reach 100%,

and then more 32 min for "Validating" and "Creating Windows 10 media"

in the end it's expected

4. Remove the USB from the healthy computer and place it in the broken one. Then restart/turn on the broken one (if needed, configure in the BIOS to boot on USB). You should now get a screen like this

Just follow the wizzard and it's done. Don't forget to remove the USB once the computer restarts or else you'll go back to the same screen.

Note: During the selection of where to install Windows, I deleted all of the existing partitions (including the System Reserved one).