@JeryGale, if you're subscribed you can have multiple computers.
You could create an Alexa routine to run a command on multiple PC's at once.
You can assign any phrase to our Alexa routine - for example "computers off".
Alexa routines can have multiple actions.
If you have the Smart Home Alexa skill enabled, your commands will show up under "Smart Home" when you add your actions.
So you could say, "Alexa, computers off" and have it run your shutdown command on all of your PC's.
Turning the computers on would require you to setup a Wake-On-Lan script. I have a command that can turn my PC on that runs on my Raspberry Pi because it's always on.