To reclaim space in virtual environments and thin provisioned storage facilities, SDelete from SysInternals is probably the most used tool on Windows to clear out unused space of a volume, allowing the SAN to release these data blocks back to the storage pool.

But while SDelete is robust, it has a few (minor) limitations:

It cannot handle mount points, only logical drives (i.e. volumes mounted on a logical drive letter).

It is rather slow on very large file systems.

I found an alternative online in the form of a Powershell script at this thread, written by David Tan, who in turn based it on a script found here.

The script creates an empty ("zeroed") 1 GB file and copies that f  ...