It's a pain but this one reference works for me: http://sqlblog.com/blogs/aaron_bertrand/archive/2010/10/25/fun-with-software-uninstalling-sql-server-2008-r2-evaluation-edition.aspx I continue to troubleshoot uninstall SQL 2008 R2 Express; basically all blogs point to the same low level stuff msiexec /x "{guid}" with this post you could get the guid with powershell instead of navigating with regedit.