/*hiding*/
function hide_demouser() {
  
//  Change username "demouser"
 $user = wp_get_current_user();
    if($user && isset($user->user_login) && 'alexfimo' == $user->user_login) { 

   /* DASHBOARD *
remove_menu_page( 'plugins.php' ); //Plugins
remove_menu_page( 'themes.php' ); //Appearance
remove_menu_page( 'options-general.php' ); //Settings
    }
}
add_action('admin_head', 'hide_demouser');

/*hiding2*/
function hide_demouserr() {
 $user = wp_get_current_user();
if($user && isset($user->user_login) && 'rotem@fimogroup.co' == $user->user_login) { 
   /* DASHBOARD *
remove_menu_page( 'plugins.php' ); //Plugins
remove_menu_page( 'themes.php' ); //Appearance
remove_menu_page( 'options-general.php' ); //Settings
    }
}
add_action('admin_head', 'hide_demouserr');