Hi there, from the message you posted, it sounds more worrying that just quitting mugen only.
you deleted your youtube account as well, and the wording in the original post sounds almost like you are planning something self harmful, which is worrysome.
are you okay? please explain exactly what you mean by "leaving this world" as people are going to be concerned for your safety and people want you to be okay at the very least, I hope you see this.