They may appear on either Windows 7, 8, or 10, using gigabytes of disk space. The $WINDOWS.~BT and $WINDOWS.~WS folders are associated with the Windows 10 upgrade process. They also contain a large amount of space several gigabytes. This folder contains files related to when you upgraded your system to the latest version of Windows 10. If you've noticed your hard drive space is low and you can't figure out why, it could be the $Windows.~BT folder. Takeown /F 'C:\$Windows.~WS\*' /A /R /D Y Can I Delete 'windows.old' and '$Windows.~BT' Folders after Upgrade from Windows 7 to Windows 10.
