Clean up after demo - how to?

I try to build a project showing all the available demos in action, switched by button press.
Before loading a next demo I clear screen objects calling lv_obj_clean(lv_scr_act()); but it seems it is not sufficient. Perhaps I should stop some timers but stopping all of them like this:

lv_timer_t* timer = lv_timer_get_next(nullptr);
while (timer != nullptr) {
  timer = lv_timer_get_next(timer);

may not be a good approach. In another words, how to bring the library to the original, fresh start state?
Please advise.