suggested changes

app/models/ability.rb

@@ -83,6 +83,7 @@ class Ability
       conference.registration_open? && !conference.registration_limit_exceeded? || conference.program.speakers.confirmed.include?(user)
     end
 
+    can :index, Organization
     can :index, Ticket
     can :manage, TicketPurchase, user_id: user.id
     can [:new, :create], Payment, user_id: user.id

app/models/organization.rb

@@ -1,5 +1,5 @@
 class Organization < ActiveRecord::Base
-  has_many :conferences
+  has_many :conferences, dependent: :destroy
 
   validates :name, presence: true