Add remove-p.php to functions.php
<?php
// Remove <p> tags around images in editors
function filter_ptags_on_images($content) {
$content = preg_replace('/<p>\s*(<a .*>)?\s*(<img .* \/>)\s*(<\/a>)?\s*<\/p>/iU', '\1\2\3', $content);
return preg_replace('/<p>\s*(<iframe .*>*.<\/iframe>)\s*<\/p>/iU', '\1', $content);
}
add_filter('acf_the_content', 'filter_ptags_on_images', 9999);
add_filter('the_content', 'filter_ptags_on_images', 9999);