Hi,
As you have notice, there is no such option in HikaMarket.
But it is possible to create a small custom plugin in order to authorize or not the deletion of an HikaShop product.
So the plugin could check the product and see if it is an approved product or not (and also see who is deleting it).
Thanks to that, you can let the "deletion" right to your vendors and the plugin will do the rest !
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.