Hi Barry,
You're welcome! I'm glad to hear that Storage Sense is already helping you free up space.
The Windows.old folder is created when you upgrade to a new version of Windows. It contains your previous version of Windows and allows you to roll back to it if needed. If you've confirmed that you don't need to revert to the previous version of Windows, you can safely delete the Windows.old folder to free up space.
To help other customers who may be facing the same issue, please click 'Yes’ underneath the post that had the solution for you. This highlights the information for other customers. Thanks for your cooperation.
Good luck with the cleanup, and I hope your Surface continues to run well with the updates!
Your Sincerely
Hahn. W - MSFT | Microsoft Community Support Specialist