app/views/opac/page/_header.html.erb
<div id="opac_header">
<% if user_signed_in? %>
<div class="opac_header_right">
<div class="opac_user_singed_in">
<img src="/assets/opac/user.png"/ class="opac_user_singed_in_icon">
<%= t('opac.login.logged_in') %>
</div>
<div class="opac_logout_button">
<%= link_to t('opac.login.sign_out'), destroy_user_session_path(:opac => true), method: :delete %>
</div>
</div>
<br style="clear: both;"/>
<% end %>
</div>