You can do it through the interface in user preferences:

1. Click on your name in the top right.

2. Select preferences

3. Set the Odoo Bot Status to Disabled

But if you want to do it programmatically, there's a field on `res.users` called `odoobot_state` that you could force to `disabled`.

addons/mail_bot/models/res_users.py

class Users(models.Model):
    _inherit = 'res.users'
    odoobot_state = fields.Selection([
        ('not_initialized', 'Not initialized'),
        ('onboarding_emoji', 'Onboarding emoji'),
        ('onboarding_attachement', 'Onboarding attachement'),
        ('onboarding_command', 'Onboarding command'),
        ('onboarding_ping', 'Onboarding ping'),
        ('idle', 'Idle'),
        ('disabled', 'Disabled'),
    ], string="OdooBot Status", readonly=True, required=True, default="not_initialized")

You can simply disable bot message by inherit one method "_get_answer" of mail.bot object.
just need to return False instead of any message.

def_get_answer(self, record, body, values, command=False):

return False

 There is the module called 'OdooBot' (mail_bot). You can find it among the apps if the filter 'Apps' is turned off.

Try to uninstall it (since it is not in dependancies to other apps) - would not it help?

to set the preference for everyone, you can run the following update for all users: 

update res_users 

set odoobot_state = 'disabled ;