deleted the presentation link

src/server/views/widget/page_tabs.html

@@ -47,15 +47,6 @@
   {# to place right side #}
   <div class="mr-auto"></div>
 
-  <!-- presentation -->
-  {% if not page.isTopPage() %}
-    <li class="nav-item d-edit-none">
-      <a href="?presentation=1" class="nav-link toggle-presentation">
-        <i class="icon-film icon-fw"></i><span class="d-none d-sm-inline">{{ t('Presentation Mode') }}</span>
-      </a>
-    </li>
-  {% endif %}
-
   <!-- revision-history -->
   <li class="nav-item d-edit-none">
     <a class="nav-link" href="#revision-history" role="tab" data-toggle="tab">