Hi,
The drop zone is working exactly like the one in the HikaShop backend.
You can upload file with an authorized extension (extensions that you can set in your HikaShop configuration).
Afterwards, if you want to remove the product file upload ; you just have to configure your HikaShop ACL to remove "product / edit / files".
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.