Thanks. It looks okay when I view your website. When I hover over the ‘Parrot’ product, the first gallery image fades in over the main image.
Have you been using the Retail theme from before the latest theme update?
It may be that your browser has cached the CSS code from the older version of the theme. If you clear your browser cache it should work correctly.
If you just want to remove it, please add this to Appearance > Customize > Additional CSS:
.product-extra-img {
display: none;
}