Not sure if you are talking about the AJAX client or Plug-in. Below is for AJAX.
By default, you cannot prevent the AJAX client showing the toolbar. However, if you want to prevent users seeing the toolbar you need to edit the opendoc.htm file. This file can be found here: C:\Program Files\QlikView\Server\QlikViewClients\QlikViewAjax
Add the following text between the head and body of the htm file:
Save the file. Note this is not standard functionality and will be over written if you upgrade to a newer build. Always document these kinds of changes so they can be implemented again after an upgrade!