Find out where the electrical comes from remove it and plug up the hole with a drywall patch who needs these just covered .

Likely low voltage.

Agreed, patch the drywall.

Make sure your smoke detector wiring isn’t linked before cutting any wires

You have to "die" the connections at the circuit breaker, Remove , patch and they're gone. A lot less trouble than a cover plate.

• You have to "die" the connections at the circuit breaker,

Hah - around here we would say "kill" - not "die" !

whatever!!!!: )

"whatever???"

Classy response!

"anybody know what kind of power is coming into each of these devices"

As you can see from these installation manuals, the remote intercoms stations any power from the master station. If you can find the manual for your master station, you can see the transformer voltage (e.g., 16 or 18 volts). Of course, if the master station has been removed you'd have do rewire the stations to provide power to them. I don't know what purpose you'd find for, say, a 16-volt low-amp circuit in each room.

That’s a great question, any suggestions for what tech or use case one could use a 16 volt low amp circuit?

Traditional doorbells use 16 volts. Some video doorbells were designed to run on 16 volts so old wiring could be reused. Inside your house? No idea.