SQL Server 2012 Install error "The instance selected for installation is already installed and clustered on computer..." I am trying to setup a new environment for SQL Server 2012 AlwaysOn. I inadvertently used some SQL Server 2008 config files initially to do the installs but ran into too many problems. I un-installed SQL Server using program features but apparently that did not remove everything.  

Now when I try to use the install wizard, I get to the "Installation Configuration Rules" screen and am presented with a failed status for rule "Existing clustered or cluster-prepared instance". If I click on the "failed" link, the dialog box says 


  Rule 'Existing clustered or cluster-prepared instance' failed. The instance selected for installation is already installed and clustered on computer SQLNode1. To continue, select a different instance to cluster."


The problem is I absolutely need to use the same instance that I had tried to previously remove. How can I ensure the previous instance has been removed so I can attempt this install again?
Installing Windows Server from scratch would remove any issues from the failed install and ensure that there are no problems going forward when patching or changing the SQL Server instance. 

If this is going to be a production server removing any chance for downtime in the future should be the biggest concern.