The reason Immortal Bot can Instant leave games is due to injection. what its doing is modifying values in the code that the player has no access to via slash commands.
Basically you have to use a hack or bot to instant leave game. there is no other option. that's just the way it is.
the reason were saying other stuff in the thread is we've TOLD you this and you've completely disregarded what we've said and continued to ask a question that has already been answered.