Hello,
It is not possible to remove an HikaMarket vendor "like that" since it is related to HikaShop sub orders, HikaShop products, etc.
The best can be to unpublish the vendor account if the "administrator user" of that vendor is deleted.
But an automatic removal is too risky.
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.