In TFS 2012,
- View the history of the thing you want to rollback.
- Select the changeset you want to roll back.
- Right click on the changset and choose “Rollback”.
- Check that the pending changes are correct (the rollback command will revert the entire changeset not just the file you selected)
- Check in.
In TFS 2010, you can call the tf rollback command from a visual studio command prompt, or you can install the TFS power tools and use the same process as above