There is an uninstall file that must be run to correctly remove the agent. It can be found:
/applications/utilities/roboshadow_uninstaller
Next, you need to delete the plist file as follows:
Go to the Finder and select Go menu and Go To Folder.
Paste or type ~/Library/Preferences and press Go.
Find the plist file that you want to delete, such as com.apple.systempreferences.plist or com.apple.desktop.plist.
Control-click or right-click the plist file and select Move to Trash. If there are two files with the same name, delete both.
Empty the Trash to complete the deletion.