How to stop a Slider
Maybe use a smarter slider? I frequently use Slick, which will only initialise when the number of items is > 1.

In addition, within my template code I would only include the markup required only for the slider if the number of slides is > 1, as I like to keep my markup clean. Something like:

  {% if entry.hero|length &gt; 1 %}&lt;div class="hero-slider"&gt;{% endif %}
    // Hero / Slider markup goes here…
  {% if entry.hero|length &gt; 1 %}&lt;/div&gt;{% endif %}