From what I see, in v2 of GMaps API there was a property \"buttons\" of the InfoWindow object that one could define in a way that given InfoWindow has no close button:
You can use this. This will not hide other images like zoom control, pan control etc. on dom ready of info window you can use this.
google.maps.event.addListener(infoWindow, 'domready', function () { document.querySelector(".gm-style-iw").nextElementSibling.style.display = "none"; });