Need a LEGAL .iso of Windows 10 Pro - Pre Anniversary Edition for clean install.

Create installation media (USB flash drive or DVD) that you can use to install a new copy of Windows 10, perform a clean installation or reinstall Windows 10.

Before you download the tool make sure you have:
An internet connection (internet service provider fees may apply).
Sufficient available data storage for the download, on a computer, USB or external drive.
A blank USB flash drive with at least 5 GB of space or blank DVD (and DVD burner) if you want to create media. We recommend using a blank USB or blank DVD, because any content on it will be deleted.
When burning a DVD from an ISO file, if you are told the disc image file is too large you will need to use Dual Layer (DL) DVD Media.

You can then download and run the media creation tool
http://go.microsoft.com/fwlink/?LinkId=691209

How to create ,ISO file.

More about downloading Windows 10 Click the web link.

 https://www.microsoft.com/en-in/software-download/windows10