Currently, we have an API call called "Delete an Experiment" https://docs.developers.optimizely.com/web-experimentation/reference/delete_experiment to archive experiments (it was suggested in another feedback to modify the name into "archive an experiment"). However, some users would like to actually delete permanently old experiments, to avoid having a very long list of archived experiments. Please consider adding a functionality (in the UI or though an API call) to permanently delete experiments.
The same could be done also to all other features that currently can only be archived, such as audiences, events, etc