В components/com_kunena/funcs/view.php
if (CKunenaTools::isModerator ( $this->my->id, $this->catid ) || !$this->kunena_forum_locked) {
//this user is allowed to post a new topic
$this->thread_new = CKunenaLink::GetPostNewTopicLink ( $this->catid, CKunenaTools::showButton ( 'newtopic', JText::_('COM_KUNENA_BUTTON_NEW_TOPIC') ), 'nofollow', 'kicon-button kbuttoncomm btn-left', JText::_('COM_KUNENA_BUTTON_NEW_TOPIC_LONG') );
}
В components/com_kunena/funcs/showcat.php
if (CKunenaTools::isModerator ( $this->my->id, $this->catid ) || !$this->kunena_forum_locked) {
//this user is allowed to post a new topic:
$this->forum_new = CKunenaLink::GetPostNewTopicLink ( $this->catid, CKunenaTools::showButton ( 'newtopic', JText::_('COM_KUNENA_BUTTON_NEW_TOPIC') ), 'nofollow', 'kicon-button kbuttoncomm btn-left', JText::_('COM_KUNENA_BUTTON_NEW_TOPIC_LONG') );
}
Вот эту строку
if (CKunenaTools::isModerator ( $this->my->id, $this->catid ) || !$this->kunena_forum_locked) {
замени на
if (CKunenaTools::isModerator ( $this->my->id, $this->catid )) {
И поидее её будут видеть только медараторы этой категории и админы