further delete (spec files)

db/migrate/20160704143402_remove_teams.rb

@@ -1,6 +1,6 @@
 class RemoveTeams < ActiveRecord::Migration
   def change
-    remove_column :exercises, :team_id, :integer
+    remove_reference :exercises, :team
     drop_table :teams
     drop_table :internal_users_teams
   end

db/seeds/development.rb

@@ -22,6 +22,3 @@ Hint.create_factories
 
 # submissions
 FactoryGirl.create(:submission, exercise: @exercises[:fibonacci])
-
-# teams
-FactoryGirl.create(:team, internal_users: InternalUser.limit(10))