Promo Image reloader

I have SIX images on the Promo image reloader, i need to delete ONLY one of them, but cannot delete while others can be deleted , Every time i press to delete this image the page redirect me to the login administration page i login again and face the same problem while other images can be deleted only this one is stuck as if it is forbidden :)

so how could i delete this image ? 

and can i delete it from:  media/images/promo

You cannot delete all, must be at least one,If you want is not to display any changes to the html block

 Yes I can delete all i did it before, it will show blank space but what i want is to delete one image from the six and it seem only this image is redirecting me while i tried to delete other images it worked but i ned to keep only 5 images and the one i want to delete is the one causing me problem

I can't think anything, you've tried clean the cache and delete your browser temporary files?

sometimes helps disable the web cache when these making changes, here advanced settings/template/ and Uncheck all options