For a gentleman player, the quickest way to leave an instance is to destroy it. However, destroying an instance isn't that easy; it's not as simple as just blowing up a few buildings. Without a considerable degree of destruction, the game won't recognize the instance as destroyed. So, there's a better way, which is to destroy the Instance Authorization Document or directly kill the instance holder.
The game rules state that when an instance is opened, the Instance Authorization Document must exist somewhere within the instance. Searching for it everywhere certainly won't work. Therefore, it's best to either level the instance buildings or kill the instance holder.
