First I suggest using a child theme (if you aren’t already), might I suggest the One-Click Child Theme. You can grab it using the plugins tab.
Be sure to have Gridster as your active theme first!
Once the plugin is installed and activated, go to Appearance >> Child Theme
Name it “Gridster – child” (or whatever you want) and save. It will automatically activate the child theme for you.
Then go back to Appearance >> Child Theme
Select “content-single.php” from the dropdown menu, click “Copy Template”
Then go to Appearance >> Editor, click on “content-single.php”, find and remove…
<ul id="meta">
<li class="datemeta"><?php echo human_time_diff(get_the_time('U'), current_time('timestamp')) . ' ago'; ?></li>
<li class="categorymeta">
<?php _e('Posted in:','gridster-lite') ?>
<?php the_category(', ') ?>
</li>
<li class="commentsmeta"><a href="<?php comments_link(); ?>">
<?php comments_number( '0', '1', '%' ); ?>
</a></li>
<li class="authormeta">
<?php _e('Author:','gridster-lite') ?>
<a class="url fn n" href="<?php echo get_author_posts_url(get_the_author_meta('ID')); ?>">
<?php the_author(); ?>
</a></li>
<li class="tagmeta">
<?php the_tags('Tags: ',', ',''); ?>
</li>
</ul>
Doing this will remove the time, posted in and categories, comment count, author info and tags…ALL of the metadata at the top of your posts.
I hope this is what you’re looking for.