https://wccftech.com/windows-10-rs5-switch-to-s-mode/

Microsoft released a fresh new build from Windows 10 Redstone 5 branch to its Fast ring and Skip Ahead Insiders yesterday. Along with other improvements and bug fixes, it appears Windows 10 Preview Build 17686 also brings a hint that the company may soon allow its users to “Switch to S Mode.”

Windows 10 S Mode is the locked down version of the operating system that is a reincarnation of Windows 10 S designed to compete against the growing market of Chrome OS. When Microsoft released Windows 10 S, users were given an option to upgrade to Windows 10 Pro. However, the company later announced turning this separate edition of Windows 10 to a “mode” that offers businesses and educational institutes offer a browser-based version of the full-grown operating system.