You don't really have to disband a guild, there is no actual need for it in Grand Fantasia, tbh.
If you're disbanding due to the name, buy a guild name change scroll instead. Well worth it when it's for a higher level guild. If you want to leave the guild to join another, just make an alt on a separate account and promote them to guild lead. You'll keep your guild to perhaps come back to later with no gold/effort wasted.