tap/app/views/users/_user.html.erb

<tr>
  <td>
    <%= user.id %>
  </td>
  <td>
    <%= image_tag user.avatar(:small) %>
  </td>
  <td>
    <%= user.nickname %>
  </td>
  <td>
    <%= euro(user.debt) %>
  </td>
  <% if current_user.admin? %>
    <td>
      <%= link_to "Delete", user_path(user), method: :delete, class: "btn btn-danger", data: { confirm: "Are you sure?" } %>
    </td>
  <% end %>
</tr>