If you are looking to either remove the Spotify integration from the Distribution tab, or remove your show from Spotify's platform, please reach out to them via this form. Their support team will be able to help with this request.
When you delete a show within Acast it will be automatically removed from other platforms (it can take up to 24 hours depending on the platform's updating frequency). But if you are rather looking to remove the show from specific platforms, it's best to reach out to them directly.