Wait a second.
If you assign null to any variable of a reference type, you don't do anything to the object itself. You modify the value of this variable (or a member of some class or structure), but this is only a reference to this object. However, as a result, the object may loose reachability
. The CLR can figure out that the object cannot be accessed from anywhere in the executing code; and in this case the object can be destructed by the Garbage Collector
(GC) — please see about reachability and garbage collection here:
Just think about it. I feel you are missing something very basic and important.
Now, this all has nothing to do with items in the list box. The items can be removed, for example, by the method