GR never, ever deletes old bookcovers. We create alternate cover editions because while there may have been very few sales of your book with its first cover there are still some readers out there who may want to see the correct copy of the book with their cover image on this website. So it wouldn't be fair to those readers, however few they may be, to remove the image that matches their copy of the book.
I will get started making an alternate cover edition for you.
I've created the alternate cover edition with the new cover. Of course I haven't read your book, but I am more attracted to your new cover. The old one kind of reminded me of the cover images from R.L. Stines' books. Does everything look right?
I will get started making an alternate cover edition for you.