By default the Blue Grace doesn’t use your email address under posts, so please check inside wordpress under Users that your username is not an email address. If you really want to hide the information open the file: wp-content/themes/blue-grace/index.php at line 53 you should fine:
<?php if (!is_singular()): ?>
<div class="endate"><?php the_author(); _e(' on ', 'blue-grace'); the_time(__(get_option( 'date_format' ), 'blue-grace')); ?></div>
<?php endif; ?>
change it to:
<?php if (!is_singular()): ?>
<div class="endate"><?php the_time(__(get_option( 'date_format' ), 'blue-grace')); ?></div>
<?php endif; ?>
and it should be gone.