I have tried to clear all histories by using $ionicViewService.clearHistory() function. However, it seems that the histories are still remaining in the memory.
The console log for $rootScope.$viewHistory.histories indicated that they are quite similar between after and before running clearHistory(). The only different is the $rootScope.$viewHistory.histories.backView is set to null. The rest of histories data is still remaining.
Is it considered as a bug in v0.9.26?