I uninstalled downloaded programs from the Uninstall Programs in the Control Panel. After I restore the system to the early date, I saw those removed programs show up again in the Uninstall Programs List but they just cannot locate the programs if I click on uninstall button. I believe the program has been removed but some items are still in my computer. So, after the system is restored to the early date, the undeleted items return to the Uninstall Programs List. Do you know how to delete all the items related to the removed programs? Where do they usually hide in the compute? Thank you for your answer.

Sometimes it happens like after even after uninstallation some file are still showing up in file explorer.
If such problem persists through file explorer search for the files associated with the software manually delete files associated with it and completely remove the software.

When you do a Restore, it restores your Registry from an earlier time. The Registry is a database of settings on your computer. So by restoring , you put back the entries in the Registry that listed the uninstalled programs. But since they have already been removed from the hard drive, you can't uninstall them again.

What you can do is use a Registry Cleaner like CCCleaner to remove orphaned entries.