Hi,
You can modify the theme and remove this buttons and contact form, for all items on your website.
Editing item.php (located at oc-content/themes/modern/item.php) find the following code and remove it.
at l.98 - l.105 (buttons code)
<p class="contact_button">
<?php if( !osc_item_is_expired () ) { ?>
<?php if(osc_reg_user_can_contact() && osc_is_web_user_logged_in() || !osc_reg_user_can_contact() ) { ?>
<strong><a href="#contact"><?php _e('Contact seller', 'modern') ; ?></a></strong>
<?php } ?>
<?php } ?>
<strong class="share"><a href="<?php echo osc_item_send_friend_url() ; ?>" rel="nofollow"><?php _e('Share', 'modern') ; ?></a></
</p>
and you need remove more code at item.php,
at l.180- l.224 (div contact seller)
<?php if( !osc_item_is_expired () ) { ?>
<?php if(osc_reg_user_can_contact() && osc_is_web_user_logged_in() || !osc_reg_user_can_contact() ) { ?>
<div id="contact">
<h2><?php _e("Contact publisher", 'modern') ; ?></h2>
<p class="name"><?php _e('Name', 'modern') ?>: <?php echo osc_item_contact_name(); ?></p>
....
</form>
</div>
<?php } ?>
<?php } ?>
For the moment we will not implement this options at core.
Thanks