It is easy to close the messaging feature for individual users.

  1. Log in as 'Admin' and in the admin menu go to 'Policies'.
  2. Click 'Add Policy' > give it a name and description, mark the box 'Override' next to Messages and select radio button 'Not allowed'.
  3. Please choose an organization, then others can also use the same policy. 
  4. Then click 'Save'.
  5. To the right of the policy you can click where there are 'Individual users' > 'No individual users', and add those users who should not be able to have the messaging function.