Deleting a user and its traces is a tuff task, which should be handled by each component integrated with CB.

The Plugin API has such an event which should be used by all integration bridges.

Obviously there are things like published posts of a user in a forums which should stay. Not all should be deleted.

Front-end user deletes can be implemented only once all or at least most of the components are integrated using that function...

Joomla itself is not handling this function either.

The API has no user-delete function in it right now. It could be a feature request for the tracker.

The CB core team has already thought about the user removal function from front-end, although this is not a joomla-feature yet...

It's not a straightforward process as you want to insure:

a) that the user-delete really comes from the user himself
b) that the user is aware of all the irreversible effects of his deletion
c) that all gets deleted what should get deleted, but no more.

a) and b) is a workflow implementation
c) is a started in the plugin API with RC2.

These are the reasons it's not implemented in core RC2.

Once c) is well-covered and tested with back-end deletes, and if possible joomla core supports it, we will move forward with a) and b).