Some PCs, including Microsoft’s Surface Laptop and the Windows on ARM PCs, run “Windows 10 in S Mode.” In S Mode, Windows can only run apps from the Store—but you can leave S Mode in a few clicks.
You can’t undo this choice. You’re free to leave S Mode at any time, but you can’t put a PC back into S Mode after leaving it. This is a one-time decision for the life of your PC’s hardware. If you decide you want to use S Mode again after leaving it—well, tough, you’re out of luck until you get a new PC in S Mode.