Delete a survey

Permanently delete an engagement survey with everything stored for it: its versions, all of its responses (with the files respondents uploaded, and the SURVEY tickets of a survey from before Surveys 2.0), its stats and analytics, its delivery records and its search index entries. The survey is gone at once; its data is deleted in the background within minutes. Live email campaigns that send it are paused (their pending sends dropped) and kept without the link; see GET /{surveyId}/delete-preview. This cannot be undone.