I'm attempting to edit a line out of the footer file in every single one of my html files on Github.
Anyway that I can do this all at one time?
Get an IDE or a decent advanced text editor and do a find and replace in project. Often this function is mapped to the keybinding Ctrl+Shift+F.
Here's a link for the Atom editor: http://flight-manual.atom.io/using-atom/sections/find-and-replace/
JetBrains editors also support this function: https://www.jetbrains.com/help/idea/2016.2/finding-and-replacing-text-in-project.html