The possibility to delete the configuration defined somewhere else is added.
E.g. if webform.webform.contact exists in the default configuration storage, you can delete in if a configuration split is enabled. To do this, add the following line to Configuration Split Ignore settings of the split:
!webform.webform.contact
This is the initial dev release of the module. It is being used in production on multiple Drupal 8 sites but requires further testing and documentation.