Hello Vincent,
I am really sorry for the delay of this reply as it is a weekend for us here. Currently you can't but you can hack the theme file which is located in /components/com_easydiscuss/themes/simplistic/post.php and at line 57 locate the codes below:
<?php if( $answer ){ ?>
<div class="discuss-answer discussAnswer">
<a name="answer"></a>
<?php echo $this->loadTemplate( 'post.reply.item.php' , array( 'question' => $post, 'post' => $answer ) ); ?>
</div>
<?php } ?>
Replace it with,
<?php if( $answer && $system->my->id){ ?>
<div class="discuss-answer discussAnswer">
<a name="answer"></a>
<?php echo $this->loadTemplate( 'post.reply.item.php' , array( 'question' => $post, 'post' => $answer ) ); ?>
</div>
<?php } ?>