You can use a USB stick obtained from the official Microsoft site by typing “get Windows 10” in the browser. The version to install is Windows 10 Home multilanguage and you must create a pendrive with the media creation tool.
Once you have it, you must perform the steps included in this tutorial, deleting all the existing partitions on the SSD and selecting the resulting unallocated space as the installation destination (points 4-8):
You will not need a new Windows key, as it will be activated automatically when connecting to the internet. The Windows key is on the motherboard.