Multiple resized images crowd the library

Hi all
I use my Minamaze Pro and other thinkup themes on my various sites. I have asked them several time to tell me how to remove all the large number of extra images that the themes generate populating my media library with unnecessary image files that are of no use at all. So far I have had no answer from them. I am a photographer and upload a lot of high quality images to my sites, and this feature in ThinkUp themes is overloading my site files.

Does anyone know where I can change the settings for this so that only the size variations I set in my WP media settings are generated? And more importantly how can one control the image sizes to limit this in any WP site?

Thanks Vishy Moghan