The recommended step for installation is to uninstall the RC version and install RTM on the Application Tier. I found a great post to follow by Martin Hinshelwoods. http://blog.hinshelwood.com/upgrading-from-tfs-2010-rc-to-tfs-2010-rtm-done/
The first step was to make sure I had all of the settings from the initial installation on hand such as the Data Tier and Service Users. I also made a list of urls for the Report Server and existing SharePoint installation. After uninstalling TFS RC and made an attempt to install RTM I was asked to Uninstall Team Explorer 2010 and Microsoft Visual Studio 2010 Shell separately from the TFS Uninstall. Just a minor difference from Martin Hinshelwood’s post. Once the installation was completed I started the RTM install wizard and chose the upgrade option. The process went as planned with no interruptions using the existing settings when prompted for credentials. I have to admit I am falling in love with the new TFS 2010.