Messages going to the Mac from my iPod
Sign out of FaceTime and Messages on the device that you want to control better.
Write down on a piece of paper all the Apple ID that are logged in to messages and FaceTime on the affected pool of devices.
De-register your cellular number from other people's AppleID at https://selfsolve.apple.com/deregister-imessage
Sign in with your AppleID on only the select devices you want to receive messages.


Test. At that point, you can ask a follow-on question with a short list of the unique accounts and unique devices and/or ask if there is an Apple support article similar to the one that documents how to remove a phone number from an email (for instance) if that's not the sticking point.