As I can see that most of our clients will show that categories on mobile too. If you want to hide when no module is assigned, I updated this block:
/templates/ja_megastore/tpls/blocks/off-canvas-categories.php
<?php if ($this->countModules('off-canvas-categories')) : ?>
<button class="off-canvas-toggle off-canvas-toggle-primary <?php $this->_c('off-canvas-categories') ?>" type="button" data-pos="left" data-nav="#t3-off-canvas-categories" data-effect="<?php echo $this->getParam('addon_offcanvas_effect', 'off-canvas-effect-4') ?>">
<i class="fa fa-bars"></i>
</button>
<?php endif ?>
so it can work that way.
Kindly check.