I'm answering my own post, as I got my problem resolved. If you ever
experience similar error, here it is how you fix it.
During the process of uninstalling CertCA, then demoting the DC and finally
reinstalling the CertCA Certreq.inc file was updated with following info.
"sServerType="StandAlone" 'vs Enterprise"
That is where the problem was. My CA is an Enterprise not StandAlone.
All I had to do is change the line to
"sServerType="Enterprise" 'vs StandAlone"
Restart the CertCA and you are running with templates available in the GUI
again.