Fix duplicated method, already in Repository::Base

app/repositories/orient_db/learning_object_repository.rb

@@ -43,13 +43,6 @@ module OrientDb
       result = connection.command "INSERT INTO LearningObject CONTENT #{learning_object.to_json}"
     end
 
-    # Usage:
-    #   repository.for(:learning_objects).destroy learning_object
-    #
-    def destroy(learning_object)
-      connection.command sprintf("DELETE VERTEX #{odb_class} where @rid = '%s'", learning_object.id)
-    end
-
     def update_property(learning_object,property,value)
       if accepted_properties.include? property
         connection.command "UPDATE LearningObject SET #{property}='#{value}' WHERE @rid = #{learning_object.id}"