Cant Uninstall SP3 from SQL Server 2008r2
I try control panel add/remove option but its remove all database instance. Please suggest


That is not exactly the place from where you can uninstall SP, you have to go to add remove programs and then on top left you would see installed updates



Click on view installed updates and you would see all updates for your computer and programs installed on it. Locate SQL Server 2008 R2 Sp3, I have SQL Server 2014 SP2 and it shows like.

Right click on the Service pack and select uninstall.