Ben Eater (eater.net) and James Bates (https://www.youtube.com/@jimmyb998) did this 7 years ago using breadboards, logic chips and eproms. They did an excellent job of documenting their designs. Although this computer sounds to be more elaborate, Ben Eater's and James Bates' work should have...
That worked. What I missed was that the user or group (in my case "Administrators") needed to be entered in the "Enter the object names to select" field of the "select Users or Groups" dialog box.
Thank you.
Resolved.
Motherboard failed. New MB wouldn't boot old HD. Installed Win 10 on SSD. Can't delete Win 7 files from HD: owned by TrustedInstaller. Don't want to reformat.