If you want to remove Lighten Software's products from your Mac, please go to Applications folder in Finder and drag the product icon to Trash.
And here is a few more steps if you want to completely uninstall Lighten software from your system:
1. Go to Applications folder in Finder and find the app icon;
2. Drag the app icon from the Applications folder to Trash.
3. Go to your home user folder, in Finder's menu, click 'Go' -> 'Go to Folder', enter ~/Library/ to open the library folder.
4. Go to Containers or Preferences folder, find the related folder or .plist file, and drag them to trash. For example, 'com.lightenpdf.pdfconverter.plist' to Trash. The file name is start with 'com.lightenpdf'.
5. Go to Documents, remove the folder which is used for storing the output file. (For PDF Converter tools)
After that your copy of an app will be completely uninstalled from your Mac.
Please go to the folder you installed Lighten Software's product. For example, C:\Program Files (x86)\Lighten PDF Converter, find unins000.exe and run it. The app will be uninstalled from your system completely.