Removing BUILTIN\Administrators

We need to remove the BUILTIN\Administrators from reporting services. I.T. personnel do not want to be able to see restricted reports. We have two department users that have been added as Content Managers and we are running reporting services under a created domain user account that we created and not a system service. I have removed BUILTIN\Administrators from the Home folder and when I check, it comes right back. Do I need to deny access to BUILTIN\Administrator on SQL Server 2005 itself? I would apprecate any suggestions.

I used the link below and followed the steps to remove the BUILTIN\Administrators group from SQL Server 2005 and SRS 2005. Hopefully this will be helpful to others.

http://www.mssqltips.com/tip.asp?tip1017