GeneratePress no longer includes Font Awesome directly in the theme. Instead, you should use the official Font Awesome plugin to add it to your site when needed.
Old Theme Version
If you’re still using the Font Awesome 4 version that was included in the theme, you can remove it super easily by going to Customize > General and checking the Load essential icons only option.
Once this option is checked and saved, it will disappear the next time you load the Customizer.