Hi,
I'm afraid that we are not able to know.
If you provide a link to your website with a little more explanations on what is missing, we might have some ideas.
But unfortunately, like that ; I clearly don't see.
More than that, the login and logout and not related to HikaShop but to Joomla itself.
Even if HikaShop propose a login form, it is just redirect the calls to Joomla core (and HikaShop do not propose logout entry point).
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.