Either use title() after you call imshow to put a caption above the image, or do this to change the name shown in the title bar of the entire figure window, whichever you meant
set(gcf,'name','Demo by ImageAnalyst','numbertitle','off')
By the way, are you creating 15 separate figures but placing only one small image on each, near the lower right corner, with the subplot() function? Because that's what it appears like and I don't know why you'd do that.
