Can you leave your current guild?

I'm currently in a really low activity guild. There are 25 members, but it seems like there are only a few of us that contribute activity points or participate in events. I've been in the guild for about 3 weeks, and we only accrued enough activity points to qualify for the Guild Wars event once. So, I really want to leave this guild and join a new one with more active players, but I can't seem to find a way to exit it. Is it even currently possible to leave your guild on your own? Or, does the guild leader have to remove you?