If you don't know what you are doing then don't delete anything you don't recognize.
Would you open your car bonnet and start ripping out wires you don't think you need?
No of course not, well don't do the same on your PC.
Windows relies on hundreds of small programs working together for it to work properly. Removing just one them could stop it working totally and you may be left with a £100 bill for an IT person to fix it all.
Many of these programs like Silverlight and so on are very small and will save almost no space on your hard drive nor speed your computer up, but they COULD stop it working.
Leave well alone.