To completely remove the languages box from pages which user sees after they login

  1. Browser to the template folder on your server
    Templates files can be found at /Templates/[Skin Name]/Default.html
    Default.html is Template file
    [Skin Name] is name of the skin you want to edit
  2. Open the Default.html page and remove the TAG [+BUILD_LNG+]
  3. This will remove the Languages Box Completely from User pages

If you have also removed the Languages box from login page then default Language selected in admin will automatically load for all users