Uninstalling SQL Server 2012, No option to select instance
When you deinstall SQL Server you have to select the correct program in the "Progams &amp; features" windows. (appwiz.cpl)




  Hint: It should be the program with no size.


Start the program and you should be guided through the de-installation routine.

If you don't see any option to de-install an instance, then you might not be running the correct program version, or you might not be on the server you are trying to de-install the SQL Server instance from.