Old icons will live quite happily in the tray area forever without affecting anything.
CCleaner gives you an option to clear the System tray:
Link Removed due to 404 Error
You can also do it manually with a registry hack by saving this code as a reg file and merging it into your registry.
Code:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\CurrentVersion\TrayNotify]
"IconStream"=-
"PastIconsStream"=-
With the manual method you have to stop and re-start explorer.exe which can be done through the Task Manager
(R-click taskbar for an open option) or re-starting the PC. Be aware that both methods restore default settings to
all the notification...