[Kingly_Krab]

You can do this, tested and made sure it worked before posting.:

quest::setguild(0, 0);

Information on quest::setguild.

quest::setguild(guild_id, rank) - Add player to "guild_id" with a "rank".

How I removed the guild.

if($text=~/Leave Guild/i)
{
	quest::setguild(0, 0);
}