Hi,
For the moment, that is not possible ; in HikaMarket or HikaShop.
We already have in our HikaMarket TODO list a point on the file management but it wouldn't be something in the image gallery.
The idea is to provide a specific interface to mange the files (the images and the downloadable files).
Because when you want to delete an image (or a file), you need to be sure that the element is not currently used by a product.
In the same way, you might want to update an image (or a file) so the different products which use them won't need to be modified.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.