Google Home devices and Apple HomePod both have voice commands to mute the microphone from across the room — “OK Google, mute the microphone” and “Hey Siri, stop listening” — but not Amazon Echo devices.
On Amazon Echo devices you have to push a mute button. But this will not help against Amazon Echo Remote devices. The remote microphone (which is push-for-use and not always on) remains available even if the main unit has the microphone array disabled.
https://www.androidcentral.com/how-disable-microphone-amazon-echo
https://www.howtogeek.com/237397/how-to-stop-your-amazon-echo-from-listening-in/