Just need to know what is a clean/fresh installation of OS? Does it mean installing the OS with a new Serial ID/Product ID? If that's the case, How/Where can I get the original Windows OS? I am currently using windows 10.
A new product key is not required for a clean install. What a clean install means is booting the original install media, wiping out your C: drive and starting over with an OS that has no additional apps installed.