I actually had a need to do this today, so I did some browsing of the Team Foundation Server – Setup forums and found these steps:
- Execute tfsconfig setup /uninstall:all.
- Drop the Tfs_Configuration, Tfs_Warehouse, and (optionally) any team project collection relational databases.
- Drop the Tfs_Analysis Analysis Services database.
- Optionally, delete any SharePoint site collections that were created.
- Optionally, delete any SQL Reporting Services folders that were created.
Unconfigured! (is that a word?)