Obsolete classes - I can find pointers to them, but how to get rid of them

PointerFinder reveals numerous pointers to obsolete classes. All of them 
seem to originate from something that appears (in the PointerFinder window) 
as either:
    #Refactoring -> Refactoring class
or
    #EventManager -> EventManager class
with lots of additional info.

I have no idea how to even reach the handles that are holding onto these 
obsolete classes, them seem to be from Squeak code. Any pointers appreciated 
:-)

Sophie