The simplest way to free up disk space on Windows 10 is by deleting old game files. In order to delete these files in Steam, you must open the classic steam client and access your library; under games and programs select Manage Game Files, then choose Remove. Its also possible that some of the following steps may be able to help with freeing up storage space as well:
•Right-click any file type listed in System File Cache (C:WindowsSystem32) •Choose Properties from a drop down menu •Under Location tab, click Move button for C drive or D drive where applicable