First of all, I think there is plenty of topics like this one, so try to use the search option before posting a new thread. Second, if you are filming with a mobile phone, then I would go with FilmoraGo which is a great app to edit your videos. Yes, they have their ad watermark at THE END, but if it bothers you that much, then you can use a regular edit of video built in mobile, and cut that end part.