Let's try now to remove an image from the list of images. Click on the icon right here; it shows an error in red "Used figure" which means you can't remove it because it's already assigned to a question or a response. To avoid this situation, first, dissociate the image from the question by selecting "none", save changes, try again to remove the image, DONE! The image is now removed because it is not assigned to any question or response. The same logic goes for removing formulas images; if it's already assigned, it will show an error. Dissociate it from any element using it, a question or a response, and it'll be removed.