Mass remove blank spaces from file names and folder names
There are apps that do this but I am not endorsing anything. In my experience, these apps save me hours, if not days, of work as often I need to rename or clean up thousands of images being imported from a camera.

Try searching for something like: Finder, Better, Rename.

Other than that -- you may have to write an AppleScript. There may be an AppleScript already out there. Search for AppleScripts, too.