How to delete files showing in .trash on Windows iCloud Drive

I use iCloud on my PC as well as my Macs, and I have a folder showing in 'iCloudDrive/.trash' folder on my PC which I just can't delete. Now, this folder does not show on my Mac or on iCloud.com which says recently deleted folder is empty.

This wouldn't be such a big issue, except that the folder in '.trash' is causing a problem with my Windows backup software as it shows lots of warnings relating to that folder.

Any advice as to how to remove it?