<ul data-orbit data-options="timer_speed:2500; bullets:false; timer_container_class: hide; timer_paused_class: hide; timer_progress_class: hide; slide_number_class: hide;">
...
</ul>
Pass the customizations in the data-options attribute. I've reset their classes to .hide, a display: none !important class.
this way, you dont modify the js or css and can go back to default by removing the customizations from data-options.