Click Mods and then the second option (forget the name, not going to load Civ5 to check). Then click the online tab. All available mods will be there (there's only 16 or so). One removes GDRs. Another apparently makes them tiny (didn't download, so I don't know). After you've downloaded it, go to the downloads tab and hit install.
After this, all you have to do is hit the check box whenever you want to turn them off.