Software needed
Steps:
- Use an Android Phone / Tablet or Emulator (LDPlayer / Nox /Bluestacks) and install Remote ADB shell on to it.
- Ensure ADB Debugging is enabled on your Firestick / FireTV and launch Remote ADB Shell on the Android device (my example was done on an android emulator)

Enter in the IP Address of your Firestick and click on connect. You firestick should show this prompt:

If you don’t see that prompt, then turn off ADB for a few seconds and turn it back on and try connecting again.
Once connected, use your device to issue the ADB commands.
A good command to know is
pm list packages
this will show all the installed apps/processes running on your device

Here are 15 of the process that I managed to remove from my device
Processes to Uninstall
com.amazon.bueller.music
com.amazon.bueller.photos
com.amazon.kso.blackbird
com.amazon.ods.kindleconnect
com.amazon.tv.csapp
com.amazon.tv.support
com.amazon.vizzini
com.amazon.ftv.glorialist
com.amazon.tv.livetv
com.amazon.aria
com.amazon.hedwig
com.amazon.alexa.externalmediaplayer.fireos
com.amazon.tv.alexaalerts
com.amazon.tv.releasenotes
com.amazon.tahoe
ADB Commands
pm uninstall -k --user 0 com.amazon.bueller.music
pm uninstall -k --user 0 com.amazon.bueller.photos
pm uninstall -k --user 0 com.amazon.kso.blackbird
pm uninstall -k --user 0 com.amazon.ods.kindleconnect
pm uninstall -k --user 0 com.amazon.tv.csapp
pm uninstall -k --user 0 com.amazon.tv.support
pm uninstall -k --user 0 com.amazon.vizzini
pm uninstall -k --user 0 com.amazon.ftv.glorialist
pm uninstall -k --user 0 com.amazon.tv.livetv
pm uninstall -k --user 0 com.amazon.aria
pm uninstall -k --user 0 com.amazon.hedwig
pm uninstall -k --user 0 com.amazon.alexa.externalmediaplayer.fireos
pm uninstall -k --user 0 com.amazon.tv.alexaalerts
pm uninstall -k --user 0 com.amazon.tv.releasenotes
pm uninstall -k --user 0 com.amazon.tahoe
See the process in action here