I actually did this on my board too, here is what I did. Before you do this, go set it to no for all your mods than apply this.
editdisplay.tpl
Find this around line 246 comment out
{if $multi_option}
{$lang.NOTIFY_MULTI}<br />
<input type="radio" name="notify_multi" value="1" id="multi_on" {$multi_on} class="form-radio" /> <label for="multi_on">{$lang.TEXT_YES}<label>
<input type="radio" name="notify_multi" value="0" id="multi_off" {$multi_off} class="form-radio" /> <label for="multi_off">{$lang.TEXT_NO}<label>
<br /><br />
{/if}Replace with
{if $user_status == "Administrator"}
{$lang.NOTIFY_MULTI}<br />
<input type="radio" name="notify_multi" value="1" id="multi_on" {$multi_on} class="form-radio" /> <label for="multi_on">{$lang.TEXT_YES}<label>
<input type="radio" name="notify_multi" value="0" id="multi_off" {$multi_off} class="form-radio" /> <label for="multi_off">{$lang.TEXT_NO}<label>
<br /><br />
{/if}
