At present, Cinema 4D cannot be uninstalled via the Maxon App.
To uninstall Cinema 4D from macOS;
Delete the Maxon Cinema 4D Rxx folder of the version you wish to delete from the Applications folder, and empty your trash.
To remove your Cinema 4D Preferences folder;
The Preferences folder can be found in your Users Library folder.
The path to this folder is Macintosh HD/User/<username>/Library/Preferences/Maxon
As this folder is hidden, hold down the Option (alt) key and go to the Mac menu Go to and select Library. There you will find the Preferences/Maxon folder.
Move the Cinema 4D Rxx_xxxxxxxx folder to the trash bin.
Alternatively, delete the entire Maxon folder if you do not use a Maxon product additionally.