Again, you can’t program the echo to say specific things. You can do that with the Sonos. But the echo is really designed to take language in and then it has its own responses.
Also, anything that you can disarm just via voice command to the echo, anyone can disarm by voice command to the echo, including by standing outside your front door and yelling at it. So probably not the best choice for voice. 
but you could certainly have echo arm the alarm by voice, using a virtual switch.
Many people just use a button key fobs where you press a button and that disarms the alarm, or different button that arms the alarm. There’s one popular one that people use that only cost $15. Similar to how you would use a button key fob to lock or unlock your car door.
The Echo is a great device, and I really like it, but it’s not really a good fit for most alarm system disarm scenarios. It would definitely work for your rearm from bed scenario, though, it’s a very good match for that. 