The Windows version of ZOC comes with an uninstall program. You can uninstall either from the ZOC program group in the start menu or via the Add/Remove Software in the Windows Control panel. 

If you want to manually remove the ZOC files, remove the ZOC program folder C:→Program Files→ZOC8, the ZOC data folder My Documents→ZOC8 Files and the registry entries Software→EmTec→ZOC8 in HKEY_CURRENT_USER and HKEY_LOCAL_MACHINE.  

On macOS the ZOC program and its configuration files are stored in the following locations
/Applications/zoc8.app
/Library/Preferences/com.emtec.*
~/Library/Application Support/ZOC*Files/
~/Library/Logs/EmTec*
~/Library/Preferences/com.emtec.*
Searching for ZOC in Finder or Spotlight should find all these files.