It should be possible to "reinit" an object property in object editor

I'm not speaking about class property but the difference between a string property and a string property not set at all for example.

This is needed for the ConfigurationSource chain, without that if you overwrite a configuration in the preference space for example it will be impossible to remove the overwrite (except by doing in in script obviously).

This looks like already supported in BaseCollection, we just need a proper button or checkbox in the object editor.