Report Option for Inappropriate Guild Names
You can take a Screenshot, and as long as you have a Character Name associated with it, I believe, you can contact the CS Team via the ‘Support’ link above/below and report the Guild Name thus.
Good luck.
You can use “inappropriate character name” — they also check guilds at the same time (as well as the other toons on the account).
As Inculpatus cedo says, you can also or instead submit a support ticket. That allows you to (a) include a screenshot and (b) explain why you think the name is egregious. Sometimes the issue is subtle enough that a first-line support person might not recognize the issue that seems so obvious to you.
John Smith: “you should kill monsters, because killing monsters is awesome.”