The simplest will be to edit the file "show" of the view "product" of your front end template via the menu Display->Views and remove the code:
<div id="hikashop_product_width_<?php echo $variant_name;?>" style="display:none;">
<?php echo JText::_('PRODUCT_WIDTH').': '.rtrim(rtrim($variant->product_width,'0'),',.').' '.JText::_($variant->product_dimension_unit); ?><br />
</div>
<?php } ?>
<?php if(isset($variant->product_length) && bccomp($variant->product_length,0,3)){ ?>
<div id="hikashop_product_length_<?php echo $variant_name;?>" style="display:none;">
<?php echo JText::_('PRODUCT_LENGTH').': '.rtrim(rtrim($variant->product_length,'0'),',.').' '.JText::_($variant->product_dimension_unit); ?><br />
</div>
<?php } ?>
<?php if(isset($variant->product_height) && bccomp($variant->product_height,0,3)){ ?>
<div id="hikashop_product_height_<?php echo $variant_name;?>" style="display:none;">
<?php echo JText::_('PRODUCT_HEIGHT').': '.rtrim(rtrim($variant->product_height,'0'),',.').' '.JText::_($variant->product_dimension_unit); ?><br />
</div>