Uninstalling Silverlight

I have Sketchup Pro installed plus Maxwell Render. I had to install Microsoft Silverlight to run Maxwell, but it told me I could only use version 4 (not the current version 5).

I deleted Silverlight 5, got hold of Version 4, but everytime I try to install it says a new version is installed. All traces of Version 5 have been deleted, but it still shows up in the System Report. I am assuming this is just a file that collects data of installed programs, but not when they are deleted.

Can someone advise me how to remove this reference to Silverlight so that I can upload the older version.

Many thanks