How to delete a large folder from my iCloud Drive

I have a fairly large amount of data on my iCloud Drive (50GB of data, in 40000 files, in 3600 directories) that I am trying to delete.

When I delete a non-empty folder via the iCloud Drive Web interface, it always returns with an error that deleting failed, and I have to try again later.

When I delete a non-empty directory with many levels of nesting from Windows explorer, then iCloudDrive.exe will be busy for a long time, after which all data is copied back to my PC from the cloud (I think I downloaded 200GB of data last week this way). It only seems to properly process deletion of individual files, not of complex folder structures.

I filed bug reports with Apple for both of the problems above, but I am still trying to get rid of this 50GB of data. I however seem to be out of options except for manually deleting the 40K files first and then removing the folders one by one (which is not really an option 🙂). Any ideas of what more I can try?