Where can i found the code for item.php to show the promotion button for sellers only, on his item page.
I have to remove auto hook code for plugin for some reason.
 

It is this function:
osp_show_item_promote

I've tried the following code but it's not showing the promote options

osc_add_hook ('item_detail', osp_show_item_promote)

You must use that function, not hook.

<?php if(function_exists('osp_show_item_promote')) { echo osp_show_item_promote(); } ?>
not working!!!!!!

function osp_show_item_promote($item) {
  if(osc_is_web_user_logged_in() && osc_logged_user_id() == $item['fk_i_user_id'] || osc_is_admin_user_logged_in()) {
    include_once 'user/item_post.php';
  }
}

Custom modifications are not covered by support, it's on you.

when am I entering the above code in item.php the right sidebar disappears?

can you please help me in why I am getting this error.

whats file "item.php" You change  ?? in Theme folder? or item file in folder osc_pay plugin ?

I put the above code in theme's folder item.php,