We can't remove the SQL 2005 Application via Add Remove Program of Windows because the SQL have a lot of the system file so MS SQL Server 2005 create Software for uninstall included the CD Installation which you can access the files follow by the Step below.
2. Double Click ARPWrapper.exe
3. choose the component for uninstall , I'd like to advise you to select the component frist.
5. So,Welcome to the Microsoft SQL Server Installation Wizard.
7. System Config Check
8. Click Next
9. Display screen for Change or Remove Instance. for you choose so you choosed the Remove
10. select Remove
13. Confirm to Uninstall -> Click Remove