(help) Having trouble with 'resetting' app-desktop in development

hello devs, I am a beginner so please don't mind.
I am also new to electron and all the codebase of joplin. I was successfully able to build it. (thanks to build.md) I want to know how to reset all the changes made to the app. delete all the notebooks, settings , preferences, config.. like if its a newly built app.
I tried git clean -f
didn't worked.
And I am also new to monorepo code base. Guide me how to learn about all that.
What is a good and fast way to understand codebase ?

rm -rf ~/.config/joplindev-desktop or equivalent for your OS.

Yup that worked. Thanks