Question about guilds

If you get into a guild is there anyway that you can quit your guild. Also if one player joins a guild do all players join it. thanks

1) To leave a guild, click the box next to your name in the guild members list. Then click Leave Guild. If you are the leader of that guild you will have to appoint a new leader before you can quit.

2) You guild membership is account based. So when your Ranger joins a guild, then so will your MOnk, Warrior, Mesmer, Necro or whatever you play.