When you upgrade these files are overwritten when the Discourse repo is pulled into your workspace (folder); so you cannot simply “comment out” lines in a file because those files will be overwritten.
Although there are myriad ways to do things in the world of tech possibilities, the generally accepted way to modify the core is via a plugin, as mentioned earlier.
Generally speaking, in this case you would override the method in that module with your code.
Best to create a development environment because you do not want to break your production application.
This is a relatively simple plugin to write, but since you are not yet experienced with this style of development, you might consider posting over in Marketplace and asking one of the well-heeled developers who make a living developing plugins to help you.
Otherwise, you can set up a development environment and have fun learning to develop Discourse plugins.