There are some areas where data may remain behind after you use TFSDeleteProject.
- The TFS Warehouse is untouched. In order to remove the data from the warehouse, it must be rebuilt. (It is important to notice that, when the warehouse is rebuilt all the historic build data that has been trimmed from the system will be removed.) Rebuilding the warehouse is accomplished using the command SetupWarehouse. For more information, see SetupWarehouse.
- The build drop locations (i.e., the location where the build binaries, build log files, and test results log files are published during the build process) are untouched. Removing the build drops must be done manually.
- Any work item tracking metadata that is shared between projects will not be deleted.
- The version control shelve set may not be deleted if there is code in the shelve set from multiple projects.
Read the full story by Aaron Block.