An update, this is also a problem for me on OSX client. And I did some research.
The client creates a hidden "Icon?" file/folder in all folder. When this is removed, the folders will be deleted just fine, my guess is that it's your client that adds that folder;
1) since it's not on google drive it self.
2) When the Icon? (or rather Icon\r file) is removed, the folder icon with the three people is reverted to the original Mac folder look, the folder will be deleted just fine from the client.
Is the solution to use an older version? Can we prevent the client from auto-update it self because this is taking up to much of my time. thanks.