I just read a post that was closed in Dec 2021 re un-installing KiCad on MacOS. The answer was good and thorough AFAIK, but I have learned something that may be of interest to other KiCad users running MacOS:
The MacPorts package manager has a KiCad package in their repository. I’ve used MacPorts for years, and the most amazing thing is that it’s so good, I wonder why anyone uses HomeBrew 
Anyway - my point is that as a MacPorts package, installation and un-installation are easily accomplished: one command line entry to install, one to uninstall.