Stop iPhone from ringing on my Mac in Mojave This was answered in 2015, but it's not working for me:

How do I stop my Mac from ringing when I get a phone call on my iPhone?

Following the instructions there and elsewhere, I've turned off "Calls from my iPhone" in Facetime, and "Calls on Other Devices" in Settings > Phone on my iPhone, but every time my phone rings, I also get a deafening ring on my Mac.
Open FaceTime.

Go to the Preferences menu

Disable the phone numbers that you don't want to ring through to your Mac.

Turn off "Calls from iPhone"