Remove several unneeded colums from events

app/models/event.rb

@@ -4,10 +4,4 @@ class Event < ActiveRecord::Base
   validates :abstract, presence: true
   validates :description, presence: true
   validates :agreement, acceptance: true
-
-  private
-
-  def self.inheritance_column
-    'something'
-  end
 end

app/models/track.rb

@@ -1,6 +1,5 @@
 class Track < ActiveRecord::Base
   belongs_to :conference
-  has_many :events, dependent: :destroy
 
   validates :name, presence: true
   validates :color, presence: true, format: {with: /\A#?[a-f0-9]{6}\z/i}

db/migrate/20150417004249_remove_unneeded_columns_from_events.rb

@@ -0,0 +1,12 @@
+class RemoveUnneededColumnsFromEvents < ActiveRecord::Migration
+  def change
+    remove_index :events, name: :index_events_on_track_id, column: :track_id
+    remove_index :events, name: :index_events_on_type, column: :type
+    remove_index :events, name: :index_events_on_user_id, column: :user_id
+
+    remove_column :events, :type, :string
+    remove_column :events, :state, :string
+    remove_column :events, :track_id, :integer
+    remove_column :events, :user_id, :integer
+  end
+end