This will safely remove all instances of obsolete classes from Squeak image
5976

| wrong |
wrong := Association allInstances
 select:  [ :a | (a key = #DefaultMap) and: [a value asString beginsWith:
'an AnObsolete'] ].
wrong do: [ :a | a value: (SMSqueakMap allInstances first) ].
Smalltalk garbageCollect.

and this will remove obsolete classes. Is it a safe way?

| set |
set := WeakSet newFrom: Smalltalk obsoleteClasses.
set do: [ :class | class becomeForward: nil. ].
Smalltalk garbageCollect.

Pavel