If you are
a member or an officer of the Guild, please click your summoner’s profile in the main interface – click "leave" beside the "Guild".
If you are
a Guild Leader or an Acting Guild Leader, you need to transfer your title of Leader to an officer before leaving the Guild. You can try to promote a member to be an officer and then transfer the title of Leader to her/him. Please note that the position of guild leader cannot be transferred again until the previous transfer has passed 72 hours.
Members selected after signing up for Guild War can’t leave the guild until this season ends.