(Note: Please download the latest Installation Guide for Team Foundation and read the Upgrade sections for details on types of upgrades and steps to perform an upgrade to TFS 2010)
Here are the steps to upgrade to TFS 2010 RTM:
1. Backup your databases! This is a best practice just in case something goes wrong.
2. Uninstall TFS 2010 Beta2. If Visual Studio 2010 Beta2 is on the box, you must uninstall that too.
3. Install TFS 2010 RTM. I
4. After TFS 2010 is installed, configure your server using the Upgrade wizard. It should be self-explanatory from there. Point to your existing databases and go.
What not to do:
DO NOT detach your collections before uninstalling Beta2. The upgrade process cannot upgrade any collections that are detached or offline.