Thanks.
Now I am getting a Windows error message: This app can't run on your PC
And cmd returns this error: Access is denied.
This is the sequence, in an elevated command prompt:
C:\Users\ME\Virtual Machines\Win10>"C:\Program Files (x86)\VMware\VMware Workstation\vmware-vdiskmanager.exe" -r Win10-disk1.vmdk -t 2 Win10-pre-allocated-disk1.vmdk
Access is denied.