In KB 918744, in the final step it said we have to remove and reattach
the content database on the virtual server to finish orphan objects
removal.

I had all SP installed. I ran pre-scan tool and read the log file.
followed this KB and used both command line tool.

However, when I tried to follow the thrid step and remove the content
database, I checked the check box and click OK, then I was back to
previous screen where I could see the content database still there.

I tried to reboot the machine and re do the last step and still not
working. Any ideas?

Thank you very much for your help.