If you do not wish to use the mobile style, you can disable it following these steps:
- Admin CP -> Settings -> Options -> Style & Language Settings -> Default Style for Old Mobile Browsers. Set 'None'.
- Admin CP -> Settings -> Options -> Style & Language Settings -> Default Style for Modern Mobile Browsers. Set 'None'.
- Admin CP -> Styles & Templates -> Style Manager. Edit any style in the mobile style list and set "Allow User Selection" to No.
Admins will always be able to use the mobile style, as they can always use any existing style and because it is not possible to delete the last mobile style.