Old guild folded in prepatch and we went our separate ways, I used to ‘own’ our WCL page and deleted it as the guild is defunct, but it still appears as my guild on my character page.
In my character/account settings it correctly displays my new guild, just not on the main character page.
This comes from the forums, so update your forum activity on blizzard’s forums by favoriting a forum post, and then you can click Update on your character page on wcl.