Delete the previous message in the channel and not output bot commands?

Question

Ruby on Rails

Hello,
1) how to delete the previous message clearly? And everything works

def open(*)
     bot.delete_message(chat_id: payload['chat']['id'], message_id: payload['message_id']-1 )
  end

If we take the situation when, for example, Message 1 was written, then Message 2, which was deleted. In fact, now there is Message 1 and it needs to be deleted. Now, in fact, Message number 1 is already payload['message_id']-2. How can this situation be resolved?
2) How to disable bot commands in the general chat?

Thanks