Delete URL field in Discover Meteor Book

I’m trying to delete the “URL” part in the Discover Meteor Book so that it is more of a chat room. I deleted and changed the post_submit.js so that the error statement return is true. When I goto the “Submit Post” and only submit in the “Text” field and no “URL”, it won’t submit.

Do I need to change anything in the post_item.js or posts.js in the lib/collections?

Most of this issue seems to be in the Chapter 7 part when the method is introduced.