def destroy
      @question_sheet.destroy
      
      respond_to do |format|
        format.html { redirect_to admin_question_sheets_path }
        format.xml  { head :ok }
      end
    end
def destroy
      @question_sheet.destroy
      
      respond_to do |format|
        format.html { redirect_to admin_question_sheets_path }
        format.xml  { head :ok }
      end
    end
mark sheet as destroyed
 DELETE /question_sheets/1