I need to modify the Rasa X UI to add some more functionalities we have been developing, so I just need to modify the templates and add/remove buttons or modify the HTML, I see some Webpack static files like main.e0eb5524.chunk.js but they are compiled. So, I think I need to modify the templates and build again if they are available somewhere. I tried to find out somewhere in the repository https://github.com/rasahq/rasa-x but I think it is moved somewhere else.
Short answer: You can’t modify Rasa X.
It’s a private repository.
Here’s the license faq that should clarify what you can do.
And the license itself.