Hmm.
If you don't like the clock, you can remove it. Click Start and navigate through "Settings" and click "Taskbar". There is a checkbox in there for "Show Clock".
The System Tray is a different matter. Those icons indicate that something is running in the background, and will remain unless you switch that thing off. There are certain items on your list that you do NOT want to switch off - resident virus protection and the firewall spring to mind!
For other ones, you'll need to go into the settings of the relevent program. Look for a setting that reads "Auto start on bootup" or something like that and disable it.