The phone is very good and we can easily root it. Inorder to manage this phone well. Rooting is one of te est way to delete applications that are not used daily.you can delete the Google music movies and play games etc. Only the google application not the system apps. At least you will use 2gb of the 4gb. You can use other Facebook applications like Facebook lite, basics, iswipe.etc every time you open an application theres a certain data added to your phone storage.
if you want to clear data of an application go to settings-appmanager-click- the application and clear data. Just to save some space on your phone .Facebook messenger are one that has a big data #oppo