How to hide it,so nobody can see it?
Welcome to Meta 
Which bot do you want to hide?
the discourse ai one
and the plugin is disabled
If you have no intention of using the bot, I supose you could just delete it.
Sorry. The reason I said that is because deleting persona users are possible, and even though I have AI Bot enabled, I donât have that @discourse_ai user.
For context @Coming it looks like you have a trial business site with us right now
Currently, trial sites get default access to ask.discourse.com via chat, hence you see the discourse_ai user in your DMs. Itâs supposed to help you get answers to any Discourse-related questions you might have.
This user is only shown to site admins, you regular community users wouldnât see it
As Moin has pointed out since itâs an admin user you are unable to delete it. The simplest way would be to either ignore or close out the chat
my test user is able to see it in search
Strange, I just created a new non-admin account on my personal hosted Business test site and I donât see a way to start chatting with the Discourse Helper Bot.
It shows nothing when I navigate to chat or try to search for the user.
You might have enabled it previously through the What's New experiment?
I didnât try it in the chat. In my screenshot, I am using the search in the header.
Maybe our definition of âusers wonât see itâ is different. You were talking about the chat, and I was talking about the visibility of the user in general.