remove extra 'categories' after uninstall?

Hello,
I installed and then removed wordpress download manager.

But, I still have an extra ‘categories’ section in my Menu area.

Screenshot here: https://www.dropbox.com/s/5aa9w06fegsvc1y/Screenshot%202015-09-28%2014.05.46.png?dl=0

Can this be removed? Is there a db table I should delete?

Thanks!

https://wordpress.org/plugins/download-manager/