You need to be the brand owner or an account admin, to change the brand owner.
Follow these steps to change the brand owner:
Go to the dashboard view where the brand tile is shown. For this you can add /dashboard at the end of your URL/Domain (e.g. brand.frontify.com/dashboard)
Click on the gear icon to open the settings
Click on the pen to change the owner under “Brand Owner”
If the gear icon does not show, you do not have permission to change the settings. You would need to contact the brand owner or an account admin and they can change the brand owner. If you need help on finding out who that is, you can contact the Frontify Support Team.