Add the following code inside the "Head Code" on the custom code tab in the project settings. Be sure to add it within the <style> </style> tags like shown in the video.

/* Hide scrollbar for Chrome, Safari and Opera */
.horizontal-slider-track::-webkit-scrollbar {
  display: none;
}

/* Hide scrollbar for IE, Edge and Firefox */
.horizontal-slider-track {
  -ms-overflow-style: none;  /* IE and Edge */
  scrollbar-width: none;  /* Firefox */
}