Install over does not provide anything for that. From Setup.exe, there is also not support for that. It is only from Programs that I was able to right click Uninstall from the entry in the list. At first, I only removed the database engine. When I tried to install, I got an error. I went into Programs and saw it was still there. So, I right click on it, selected Uninstall and checked to remove the database engine, SSMS and database connectivity. Then, I was able to run Setup.exe ok.

Setup.exe did prompt for a message that I had to reboot before doing that. So, I clicked OK. It did continue however with the installation. It seemed to be ok. However, the final form says that some components did not install. So, I rebooted. I then restarted the Setup.exe. This time it went ok.

However, big surprise, when I went back into SSMS to connect, I had to enter ComputerName\MyInstance. With SQL Server 2012, is the computer name mandatory to be put at first?