app/views/kaminari/_prev_page.html.erb
<% if current_page.first? %>
<li class="prev disabled"><%= link_to raw(t 'views.pagination.previous'), "#", :rel => 'prev', :remote => remote %></li>
<% else %>
<li class="prev"><%= link_to raw(t 'views.pagination.previous'), url, :rel => 'prev', :remote => remote %></li>
<% end %>