title: Cannot delete a chat message via Slack API
body: <p>I have a Slack team with a public channel.
  My goal is to use the channel only for announcements posted by bot-A.</p>
  
  <p>I understand that it is not possible to configure Slack channel to be writable for only one person and read-only for the rest, I created a bot-B (Python thing running on an external machine) that monitors the channel via RTM and if there is any message not coming from bot-A, bot-B's task is to delete the message by calling chat.delete (<a href="https://api.slack.com/methods/chat.delete" rel="nofollow">https://api.slack.com/methods/chat.delete</a>). Bot-B is also in the channel.</p>
  
  <p>Unfortunately bot-B is getting "cant_delete_message" which, according to the chat.delete doc, means that he has no permissions.</p>
  
  <p>However, according to <a href="https://api.slack.com/bot-users" rel="nofollow">https://api.slack.com/bot-users</a>, chat.delete is allowed for Custom Bots.</p>
  
  <p>So is my bot-B not a "Custom Bot"? If so, what does a Custom Bot actually is and how can I create one?</p>
  
  <p>Or what am I doing wrong?</p>