Remove Categories and Tags from Admin Dashboard

I'm using my own taxonomy for blog posts and would like to remove Categories and Tags from the Dashboard. I've removed them from the Admin Menu and the meta boxes on the Edit Posts page from this question here: Remove Categories / Tags From Admin Menu

But now I'm trying to remove it from the All Posts page in the Dashboard where it shows a list of all the posts in a table and across the top are Title, Author, Categories, Tags, Date, etc. I can't seem to find how to do this.

via Chebli Mohamed