is there anyway i can hide menu bar from guest so only members can see once they are login to the site?

in your themes/default folder (change default to whatever style you use) open page.tpl.php

find:
[code]<div id="jcow_community_menu">
<ul class="menu">
<?php
echo '<li '.check_menu_on('home/index').'>'.url(uhome(),t('Home')).'</li>';
if (is_array($community_menu)) {
foreach ($community_menu as $item) {
echo '<li '.check_menu_on($item['path']).'>'.url($item['path'],t($item['name'])).'</li>';
}
}
?>
</ul>
</div>[/code]

replace with:
[code]<?php
if (!$client['id']) {
echo '
<div id="jcow_community_menu">
<ul class="menu">';
echo '<li '.check_menu_on('home/index').'>'.url(uhome(),t('Home')).'</li>';
if (is_array($community_menu)) {
foreach ($community_menu as $item) {
echo '<li '.check_menu_on($item['path']).'>'.url($item['path'],t($item['name'])).'</li>';
}
}
echo '
</ul>
</div>';
}
?>[/code]

I've not tested it, but it should work fine.

its hiding menu from logged in members i want to hide from guest?

woops! my mistake :S

try this replacement:
[code]<?php
if ($client['id']) {
echo '
<div id="jcow_community_menu">
<ul class="menu">';
echo '<li '.check_menu_on('home/index').'>'.url(uhome(),t('Home')).'</li>';
if (is_array($community_menu)) {
foreach ($community_menu as $item) {
echo '<li '.check_menu_on($item['path']).'>'.url($item['path'],t($item['name'])).'</li>';
}
}
echo '
</ul>
</div>';
}
?>[/code]

thanks eeji now it worked fine :)

great work. thanks eeji!