How to uninstall the SQL Server 2008 SP 2?
This Feature is in introduced in SQL Server 2008 SP1 and above.
Before you do the activity, it is recommended to take a full instance backup just in case to recover if anything goes wrong.
Check the Current Service pack level of the SQL Server Instance.
Go to "Programs and Features" options in Control Panel and click on "view installed updates"
Highlight the Service Pack you want to uninstall and click "Uninstall"
The uninstall Service Pack for SQL Server wizard will now come up and click "Next" here once the update rules have been verified.
Select the features for which you need to remove service pack and click "Next"
Once the file check is completed, Click "Next"
Verify the Summary and click "Remove"
Wait for the process to complete
Once this is completed, Restart the computer to finish the SQL Server Setup.
Now verify the changes