Hello,
You're doing it the exact same way you remove product images in the HikaShop backend.
By clicking on the delete button over the image.
Regards,
PS: And when you post a message, we are expecting that you fill ALL fields regarding your HikaShop, HikaMarket and Joomla version.
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.