This application is just a video splitter. This means it has the capability of cutting, trimming, and saving the output to another video or audio format. It doesn't have the feature to remove someone's face. You will need a capable video editor that offers you the possibility of applying blur to someone's face or a clone stamp tool to completely eliminate it.
You can use the tutorials on Google Search to learn how to do it since the process is a bit complicated.
Tutorials: https://goo.gl/uwPOKU