Ok, if you want to get rid of some icons from the taskbar, then go to start>run> type msconfig . Go to startup tab and uncheck what you don't need and it isn't vital...and restart.
Or do you mean the icons that remain in the taskbar after uninstaling something?
For past icons:
Go to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\TrayNotify
Delete IconStreams and PastIconsStream
DO NOT EDIT/DELETE ANYTHING ELSE IN THERE !