Get swf-to-gif.exe from the link above. It's a good experience to check the file for malware. So, use your antivirus program or try a free one – Avira Free Antivirus. Download the 2.9 MB installation file, click on it and use the setup instructions.
You can easily uninstall WonderFox SWF to GIF Converter. Click the Control Panel and choose the program you need to remove. Click on Uninstall to delete it.