Warning 26003 : Uninstall "SQL 2008 R2 Express" (Common Files & Database Engine Shared) Error
After investigation come to know that still some files of previous installation are in server.
So while removing the files from control files got below error. I was not able to remove the installation files from control panel.
Below is the solution for this error.
1) Make sure you have administrative rights on the computer and backup all the user databases.
2) Uninstall the existing SQL Server and all the components from the control panel. Remember to backup the user databases before uninstalling SQL Server.
3) Backup (Export) the registry.
4) Delete the following keys in regedit:
--HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server--HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSSQLServer
5)Goto HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall and delete all the sub-keys referencing SQL Server.
6) Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services and delete all the keys referencing SQL Server.
7) Rename / Delete all the SQL Server folders in the computer.
8) Reboot the machine.
9) Install SQL Server again.