Brands can only be dismissed when they have certain status values. Dismissing a brand will set its status to "Draft".
You sent a dismiss request for a brand that is in status "Draft" or "Rejected".
You're only interested in dismissing a brand to update its information before being vetted by Twilio's vetting team, or if you want to remove its verified status. To dismiss the brand its status must be one of "Pending Verification" or "Verified".