You won’t be able to remove that alias. Instead you should use the Alias Management Admin Portlet and change the target of where the alias.
The Alias Management Portlet is in the Admin Dashboard → Portal Configuration. Perform a search for “auth.scheme.default” and edit the alias to point at your new AuthScheme “auth.scheme.ntlm”.
As far as restricting access goes, please remember that Authentication is completely independent of Authorization. Just because a user is authenticated or Identified using the NTLM authentication scheme, doesn’t give the user any more access rights to a page. You can still fully administer what users, groups and roles have permissions to see what pages using Portal 6.5.2 ACL management.
Regards,
–mark
#webMethods-BPMS#MWS-CAF-Task-Engine#webMethods