A United States Senator has obtained a response to a letter sent to Amazon HQ concerning user privacy as it relates to the retail giant's Alexa platform. It advised the public representative that, although a given user can delete their own voice data from their accounts at will, the voice assistant's responses to queries are recorded and retained by Amazon for its own purposes.
https://www.notebookcheck.net/Amazon-keeps-records-of-users-Alexa-interactions-and-may-not-delete-them.427128.0.html