Yes, to hide the menu, just comment out the navigation items you don't want, using regular html comment blocks <!-- and -->. Edit themes/yourtheme/theme.php, find// HTML template for main menu
$template_main_menu = <<<EOT
<span class="topmenu">
<!-- BEGIN album_list -->
<a href="{ALB_LIST_TGT}" title="{ALB_LIST_TITLE}">{ALB_LIST_LNK}</a> ::
<!-- END album_list -->
<!-- BEGIN my_gallery -->
<a href="{MY_GAL_TGT}" title="{MY_GAL_TITLE}">{MY_GAL_LNK}</a> ::
<!-- END my_gallery -->
<!-- BEGIN allow_memberlist -->
<a href="{MEMBERLIST_TGT}" title="{MEMBERLIST_TITLE}">{MEMBERLIST_LNK}</a> ::
<!-- END allow_memberlist -->
<!-- BEGIN my_profile -->
<a href="{MY_PROF_TGT}">{MY_PROF_LNK}</a> ::
<!-- END my_profile -->
<!-- BEGIN faq -->
<a href="{FAQ_TGT}" title="{FAQ_TITLE}">{FAQ_LNK}</a> ::
<!-- END faq -->
<!-- BEGIN enter_admin_mode -->
<a href="{ADM_MODE_TGT}" title="{ADM_MODE_TITLE}">{ADM_MODE_LNK}</a> ::
<!-- END enter_admin_mode -->
<!-- BEGIN leave_admin_mode -->
<a href="{USR_MODE_TGT}" title="{USR_MODE_TITLE}">{USR_MODE_LNK}</a> ::
<!-- END leave_admin_mode -->
<!-- BEGIN upload_pic -->
<a href="{UPL_PIC_TGT}" title="{UPL_PIC_TITLE}">{UPL_PIC_LNK}</a> ::
<!-- END upload_pic -->
<!-- BEGIN register -->
<a href="{REGISTER_TGT}" title="{REGISTER_TITLE}">{REGISTER_LNK}</a> ::
<!-- END register -->
<!-- BEGIN login -->
<a href="{LOGIN_TGT}">{LOGIN_LNK}</a>
<!-- END login -->
<!-- BEGIN logout -->
<a href="{LOGOUT_TGT}">{LOGOUT_LNK}</a>
<!-- END logout -->
<br />
<a href="{LASTUP_TGT}">{LASTUP_LNK}</a> ::
<a href="{LASTCOM_TGT}">{LASTCOM_LNK}</a> ::
<a href="{TOPN_TGT}">{TOPN_LNK}</a> ::
<a href="{TOPRATED_TGT}">{TOPRATED_LNK}</a> ::
<a href="{FAV_TGT}">{FAV_LNK}</a> ::
<a href="{SEARCH_TGT}">{SEARCH_LNK}</a>
</span>
EOT;
and replace with// HTML template for main menu
$template_main_menu = <<<EOT
<span class="topmenu">
<!-- BEGIN album_list -->
<!--<a href="{ALB_LIST_TGT}" title="{ALB_LIST_TITLE}">{ALB_LIST_LNK}</a> ::-->
<!-- END album_list -->
<!-- BEGIN my_gallery -->
<!--<a href="{MY_GAL_TGT}" title="{MY_GAL_TITLE}">{MY_GAL_LNK}</a> ::-->
<!-- END my_gallery -->
<!-- BEGIN allow_memberlist -->
<!--<a href="{MEMBERLIST_TGT}" title="{MEMBERLIST_TITLE}">{MEMBERLIST_LNK}</a> ::-->
<!-- END allow_memberlist -->
<!-- BEGIN my_profile -->
<!--<a href="{MY_PROF_TGT}">{MY_PROF_LNK}</a> ::-->
<!-- END my_profile -->
<!-- BEGIN faq -->
<!--<a href="{FAQ_TGT}" title="{FAQ_TITLE}">{FAQ_LNK}</a> ::-->
<!-- END faq -->
<!-- BEGIN enter_admin_mode -->
<!--<a href="{ADM_MODE_TGT}" title="{ADM_MODE_TITLE}">{ADM_MODE_LNK}</a> ::-->
<!-- END enter_admin_mode -->
<!-- BEGIN leave_admin_mode -->
<!--<a href="{USR_MODE_TGT}" title="{USR_MODE_TITLE}">{USR_MODE_LNK}</a> ::-->
<!-- END leave_admin_mode -->
<!-- BEGIN upload_pic -->
<!--<a href="{UPL_PIC_TGT}" title="{UPL_PIC_TITLE}">{UPL_PIC_LNK}</a> ::-->
<!-- END upload_pic -->
<!-- BEGIN register -->
<!--<a href="{REGISTER_TGT}" title="{REGISTER_TITLE}">{REGISTER_LNK}</a> ::-->
<!-- END register -->
<!-- BEGIN login -->
<!--<a href="{LOGIN_TGT}">{LOGIN_LNK}</a>-->
<!-- END login -->
<!-- BEGIN logout -->
<!--<a href="{LOGOUT_TGT}">{LOGOUT_LNK}</a>-->
<!-- END logout -->
<!--<br />-->
<!--<a href="{LASTUP_TGT}">{LASTUP_LNK}</a> ::-->
<!--<a href="{LASTCOM_TGT}">{LASTCOM_LNK}</a> ::-->
<!--<a href="{TOPN_TGT}">{TOPN_LNK}</a> ::-->
<!--<a href="{TOPRATED_TGT}">{TOPRATED_LNK}</a> ::-->
<!--<a href="{FAV_TGT}">{FAV_LNK}</a> ::-->
<!--<a href="{SEARCH_TGT}">{SEARCH_LNK}</a>-->
</span>
EOT;