not by configuration. you need either to edit the label control or replace the help image with a 1x1 transparent gif.

You can also do this (provided you have access to the file - root\controls\labelcontrol.ascx):

    <asp:linkbutton id=cmdHelp tabindex="-1" runat="server" CausesValidation="False" enableviewstate="False">
<% If DotNetNuke.Security.Permissions.TabPermissionController.HasTabPermission("EDIT") Then%>
           <asp:image id="imgHelp" tabindex="-1" runat="server" imageurl="~/images/help.gif" enableviewstate="False"></asp:image>
<%Else%>
&nbsp;&nbsp;
<%End If%>
    </asp:linkbutton>

This way administrators can still see them and users will not (no-break space characters are added per Mitchel's comment above.)