In the file ow_system_plugins\base\classes\console_event_handler.php
comment the highlighted lines
$item = new BASE_CMP_ConsoleItem();
$item->setControl('<span class="ow_signin_label'.(empty($buttonList) ? '' : ' ow_signin_delimiter').'">' . $language->text('base', 'sign_in_submit_label') . '</span>' . $iconListMarkup);
$event->addItem($item, 2);
OW::getEventManager()->bind('base.add_page_top_content', array($this, 'addSignInCmp'));
OW::getDocument()->addOnloadScript("
$('#".$item->getUniqId()."').click(function(){new OW_FloatBox({ \$contents: $('#base_cmp_floatbox_ajax_signin')});});
");
$item = new BASE_CMP_ConsoleButton($language->text('base', 'console_item_sign_up_label'), OW::getRouter()->urlForRoute('base_join'));
$event->addItem($item, 1);