You would think that this would be a simple process. Unfortunately, uninstalling SQL Server is not as cut and dry as you would think. There have been situations in the past in which I had to uninstall and then reinstall SQL Server. I quickly found that opening up the control panel and selecting to uninstall the instance of SQL Server was not enough. Doing it that way also caused problems when trying to reinstall. So here is a short, step by step guide that works beautifully.
First, open up the control panel and go to ‘Uninstall a Program’. Select the Microsoft SQL Server Browser and click uninstall.
Next, select Microsoft SQL Server 2008 (R2 in my case) and click uninstall. This will remove the SQL Server instance and all the extra components.
There is still one more thing to complete the uninstall. Even though the instance is gone, all the database files are still in the program files directory. This will cause issues when you try to reinstall. Go into the program files, find the Microsoft SQL Server folder and delete it.
At this point, you have removed all traces of SQL Server. You can easily reinstall it with no issues.