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The $WINDOWS.-BT and $WINDOWS.-WS folders are located in the root directory of the system drive, typically the 'C' drive. By default, these folders are set to be hidden. Therefore, users need to configure File Explorer to view these folders.
Refer to Mytour's article on showing hidden folders in Windows 10 to learn how to configure File Explorer to display hidden folders.
Understanding $WINDOWS.-BT and $WINDOWS.-WS Folders on Windows 10
The $WINDOWS.-BT and $WINDOWS.-WS folders are created on Windows 10 computers during the upgrade process to the latest version. For instance, these folders are generated when users upgrade from Windows 10 Creators Update to Windows 10 Fall Creators Update.
The $WINDOWS.-BT folder contains installation files from the previous version of Windows 10, used for downgrading to the previous version. The installation files used by Windows setup or Media Creation Tool are stored in the $Windows.-WS folder.
Since $WINDOWS.-BT and $WINDOWS.-WS are system folders containing important files, many users may wonder if it's safe to delete these folders. The answer is yes, if you don't intend to revert to the previous version, you can safely delete these folders. Deleting these folders means you won't be able to revert to the previous version of Windows 10.
Important Note: Deleting these folders will prevent you from reverting to the previous version of Windows.
How to Delete $WINDOWS.-BT and $WINDOWS.-WS Folders on Windows 10
Step 1: Open This PC. Right-click on the Windows 10 installation drive, select Properties to open the Properties window.
Step 2: In the Properties window, on the General tab, click the Disk Cleanup button. This action opens the Disk Cleanup tool.
Step 3: On the Disk Cleanup window displayed on the screen, click the Clean up system files button.
Step 4: Finally, check the boxes for Previous Windows installation(s) and Temporary Windows installation files, then click OK.
In the confirmation dialog, click Delete Files to confirm the deletion of the files. The Disk Cleanup tool will delete the $WINDOWS.-BT and $WINDOWS.-WS folders, and the files within these folders.
Note that selecting the Previous Windows installation(s) option will delete both the $Windows.-BT and Windows.old folders. Similarly, selecting the Temporary Windows installation files option will delete the $Windows.-WS folder. So, choose both options to delete the $WINDOWS.-BT and $WINDOWS.-WS folders.
Here, Mytour has just guided you on how to delete the $WINDOWS.-BT and $WINDOWS.-WS folders on Windows 10. Note that Windows 10 will automatically recreate these folders when you upgrade to the latest version of Windows 10. Repeat the steps above to delete the $WINDOWS.-BT and $WINDOWS.-WS folders.
