Hi jross
To remove the mask, you can open the file: /templates/ja_fit/acm/features-intro/tmpl/style-3.php
At approx line 50, comment or remove this line:
<div class="mask"></div>
If you meant to remove the background color which covers the images, you can use this custom css to remove it:
.acm-features.style-3 .features-item-inner .features-img {
background-blend-mode: inherit !important;
}