How do I stop all messages going to all devices EXCEPT my iPhone?
How do I stop receiving messages going to my Apple Watch, iPad and Mac? And only receive messages on iPhone?
Question marked as
Setting->Messages->Text Message Forwarding, and turn off devices you don't want.
This will prevent all SMS texts from going onto other devices.
For iMessages (between Apple devices), you will need to sign out of iMessage on each device you do not want to have receiving messages.