On the advice of
spyder-ide.org is used the 'Standalone Installer for macOS'.
This appears to be specific to macOS 10.15+ which I did not know. Spyder will not start and the Traceback mentions a frame "build for MacOS X 10.15". I only have macOS 10.13.
Two questions. (1) How can I uninstall this Spyder.app thoroughly? (2) Is there a better way to install - such as the standalone for 10.13?