Remove system files on JN

Hi there, I used jupyter notebook sometime ago but now I just start installing it and play it around again, however, I found that there are lots of .dll and .exe files already on the dashboard as soon as I just got the JupyterHub newly reinstalled.

May I know if I can remove them? If not, how to reduce the volume of it since it is hard to work on it if too much irrelevant files in placed. Thanks!