How to reset Jupyter notebook settings?

I tried opennb which changes my jupyter notebook displayed in my browser really ugly like


but I want to go back to the classic settings. I undo it and uninstalled opennb, the problem is still there. Also I use conda to uninstall notebook and re-installed it, but I fail again. What should I do to go back to the classic settings? (Like my nbextensions will display around File,Running buttons)

Do I need to uninstall anaconda and re-install it?