Amazon gives no real solution to disable the microphone on your Fire Stick remote. Some claim it only records while pressing the Alexa button, however, this is clearly not true. Check your device settings on your Amazon account for a list of all Alexa recordings. Alexa does offer to record things like smoke alarms and breaking glass, but that's not why you're here.
Completely remove the microphone from the remote.
Step 1: Materials Needed
-Flat tip screw driver
-Thin plastic pry tool (like a guitar pick)
-Pliers or tweezers
-Super glue (I prefer the gel type since it stays in place)
Step 2: Open the Remote
The remote is glued together on little tabs every few millimeters all along the sides and a strip of points under the battery compartment.
1) Remove the back cover and batteries.
2) Use a screw driver to pry a small gap on the side. Try to stay closer to the microphone side of the remote.
3) Use a thin piece of plastic like a guitar pick to slide along the glue points. You'll hear a slight popping of the glue joints breaking.
4) Focus on the top half of the remote where the Alexa button and microphone are. You only need a 1cm gap to get pliers in there. The fewer tabs you have to re-glue, the better.
Check this video to watch a detailed demonstration: https://m.youtube.com/watch?v=voBQK0ndMjE
Step 3: Remove Microphone
Once you can peer inside, you'll see a little silver square by itself at the topmost of the circuit board. You guessed it, that's the microphone.
1) Use your pliers or tweezers to grasp it firmly and rotate just a few degrees, it will easily pop off.
In no way will this impair the other functions of your remote, except of course... Alexa. She'll be dead. But you still have the phone app. ;)
Pressing the microphone button will still cause your device to flash blue and expect to hear a command, but it will just record static.
Step 4: Reassemble the Remote
The only thing we have left to do is glue the remote back together. Gel super glue is great because it stays where you put it.
1) Pry the remote open just enough to get your glue tip in there. The top of each broken tab should appear slightly white.
2) You dont need to glue every tab, just a small section on each side and the top end near the former microphone.
3) Hold firmly until the glue dries.
4) Insert batteries and attach the cover, hopefully you didn't mangle the tabs to bad while prying.