Hi Brian,
I do *lots* of CIFS / NAS Folder and File re-structuring, and for *years* have been wanting a controller-side feature for deleting QTREE + data or deleting volume subfolder(s) + data.
There is a 'QTREE delete' command available (I think only a GUI feature) but it only deletes *empty* QTREEs - you have to have previously used a Windows/Linux host to delete the actual data.
From your question notes, it looks like you are trying to use Windows Explorer/GUI to delete large folders (+subfolders and files). The drawback of which is that Win Explorer has to enumerate the data before starting the actual delete process.
Instead, you can use the 'RMDIR' command from the Windows Command line. It skips the enumeration process and starts deleting files and folders immediately.
eg to delete a 2TB size second-level folder (and all subfolders and data) under a top level network share called 'Projects' :
c:>RMDIR /S /Q \\server\Projects\second-level
/S = (run recursively on all subfolders, files) /Q = (quiet mode, disable confirmations)
Thats it - the command will traverse the subtree and delete the data.