Every programming langue has its own way of dealing with comments. In Linux, by far the most common way to comment files is with the # symbol.
This is true for most configuration files and true for bash scripts. Simply put a # symbol in front of the line you want to turn “off” and it is as simple as that. For lua type configuration files (if you happen to be using the awesome windows manager) the comment symbol is —
It is also a good idea to write yourself a note to a line you may have commented or uncommented out. That way you can remember if you ever need to edit the configuration file again why you did what you did. Notes are super helpful and friendly.
I also quickly show off nano, a text based editor for the terminal. Although I don’t use it that often, it is great to know the very basics! If you fail to get a graphical user interface started but are able to get to a terminal and or shell, nano is an excellent tool to edit text/configuration files in hopes to fix up your system should you have edited something you weren’t suppose to edit (yes I have been there).