If you’re worried about stories you may have seen about Amazon employees listening to what people say to Alexa, there is something you can do about it. You can turn off your devices microphone using either software or a switch. Of course that defeats the purpose of a voice activated digital assistant, but it can give you peace of mind and you can always turn it on again if you need it.
Rather than re-invent the wheel, here’s a link to an article in VentureBeat on How to keep Alexa, Cortana, Siri, Google Assistant, and Bixby from recording you, including ways to delete recordings already made.