As you have seen, if you have been following the tutorial, from working in the protected editor, you cannot delete images unless you allow unprotected editing. But your Translator does not have that option, so what about images?
Well, in most cases you do not need to translate images. Images only need translating if they have text in them, i.e. screen shots of your program. When we designed Fast-Help International and the Translation Assistant we thought long and hard about the need for this. Our conclusion was that the likelihood was the Translator would not be asked to recreate your graphics, or touch them up or take new screen shots. And in fact that could be a very complex and expensive route. We determined that it was more likely that the person who took the screen shots in the first place was best placed to take new ones for the specific language.
Each Translation Language has its own Images folder. Images here are overwritten from the Base Language's Images folder only if they are newer in date and time than the Translation Languages images. So, as long as the Translation Images are more up to date than the Base Language's then the best advice is to take new screen shots, where applicable, and overwrite the images in the Languages Images folder. You will see that Fast-Help International refreshes itself automatically when you compile, so you don't need to update the editor when just updating the images.