BleachBit did not remove Windows old files


So I just updated my Windows 10.. Windows version is as follows -
Version 1909 (OS Build 18363.752)

I have the latest version of BleachBit and that is version

I ran BleachBit and selected all the checkboxes except for the "Free disk space" under the System menu but the Windows.old folder is still there and it occupies around 15 GB

Is this a bug or something?

BleachBit version:
Your operating system: 
Windows 10