Solved. I used <!-- comment --> to comment out the code. In Category.tpl, I commented out the following, and it worked. It was more than I thought I needed to comment out.
<!-- <div id="category-banner">
{if !empty($lazy_load)}
<noscript>
<img src="{Link::getGenericImageLink(
'categories',
$category->id_image,
'category',
(ImageManager::retinaSupport()) ? '2x' : ''
)|escape:'htmlall':'UTF-8'}"
alt="{$category->name|escape:'html':'UTF-8'}"
title="{$category->name|escape:'html':'UTF-8'}"
width="{getWidthSize|intval type='category'}"
height="{getHeightSize|intval type='category'}"
class="img-responsive"
>
</noscript>
{/if}
<picture class="img-responsive{if !empty($lazy_load)} tb-lazy-image{/if}">
<!--[if IE 9]><video style="display: none;"><![endif]-->
{if !empty($webp)}
<source {if !empty($lazy_load)}srcset="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNkYAAAAAYAAjCB0C8AAAAASUVORK5CYII= 1w"
data-{/if}srcset="{Link::getGenericImageLink(
'categories',
$category->id_image,
'category',
(ImageManager::retinaSupport()) ? '2x' : ''
)|escape:'htmlall':'UTF-8'}"
title="{$category->name|escape:'html':'UTF-8'}"
type="image/webp"
>
{/if}
<!--[if IE 9]></video><![endif]-->
<img {if !empty($lazy_load)}srcset="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNkYAAAAAYAAjCB0C8AAAAASUVORK5CYII= 1w"
data-{/if}srcset="{Link::getGenericImageLink(
'categories',
$category->id_image,
'category',
(ImageManager::retinaSupport()) ? '2x' : ''
)|escape:'htmlall':'UTF-8'}"
{if !empty($lazy_load)}src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNkYAAAAAYAAjCB0C8AAAAASUVORK5CYII="{/if}
alt="{$category->name|escape:'html':'UTF-8'}"
title="{$category->name|escape:'html':'UTF-8'}"
width="{getWidthSize|intval type='category'}"
height="{getHeightSize|intval type='category'}"
class="img-responsive"
>
</picture>
</div> -->
Hope this helps someone in the future.
pb4sc