ISO files of the March Update (build 10041) are now available for download. You’ll still receive this update automatically via Windows Update, but if you prefer a clean install or you want to install on a virtual machine, you can download an ISO file instead. Here’s how:
Click one of the Download links on this page to download an ISO file that you can use to install the preview.
When the download is complete, transfer the ISO file to installation media such as a USB flash drive or DVD.
Boot your PC from the installation media, and then follow the steps to perform a clean install.