There's a couple of things you can do, firstly you can simulate a click in switches, if you wanted to go that way, on switches there is a handy function for testing -
void pushSwitch(pinid_t pin, bool held);
However, preferably you can use the navigation facilities on menu manager (menuMgr) -
void MenuManager::navigateToMenu(MenuItem* theNewItem, MenuItem* possibleActive, bool customMenu)
void MenuManager::resetMenu(bool completeReset) // complete reset - true means go back to root, otherwise one level back