how to get rid of multiple unused text boxes

In a 350 page book, I'd often have to change page masters when edits came in causing text to reflow. And quite often while applying the new master, a new (blank) text box would be placed underneath the text already in the document. If I caught it, I'd just delete that now extra text box, but I know there are a lot of them just sitting there under the text boxes that contain the book's content.

So:

A. Is there a way to find and delete all those unused text boxes?

B. Should I just leave them (They aren't causing any problems... it just seems weird / possibly a bad idea to have them sitting there...)

C. How to avoid this is in the future.