Reduce the number of image sizes saved

all things goes to your child-theme functions.php:

this is how you can avoid responsive Image functionality in WP:

add_filter('wp_get_attachment_image_attributes', function($attr) {
   if (isset($attr['sizes'])) unset($attr['sizes']);
   if (isset($attr['srcset'])) unset($attr['srcset']);
   return $attr;
}, PHP_INT_MAX);
add_filter('wp_calculate_image_sizes', '__return_false', PHP_INT_MAX);
add_filter('wp_calculate_image_srcset', '__return_false', PHP_INT_MAX);
remove_filter('the_content', 'wp_make_content_images_responsive');

this is too WP related:

// Remove unneeded WP image sizes
add_filter( 'intermediate_image_sizes_advanced', 'prefix_remove_default_images' );
// Remove default image sizes here. 
function prefix_remove_default_images( $sizes ) {
// do NOT remove small and medium sizes, they are used in backend Media Library!
// unset( $sizes['small']); // 150px
// unset( $sizes['medium']); // 300px
 unset( $sizes['large']); // 1024px
 unset( $sizes['medium_large']); // 768px
 return $sizes;
}

And this is for Enfold Functionality: Choose the needed Image Formats yourself:
some are commented-out feel free to get rid of them too – allthough the reason for usage is described:

// Disable loads of Enfold & WP image sizes upon upload
// do image sizes manually, double-size with high compression for retina screens
// use Photoshop to set exact double size and quality between Q30 and Q40
add_action('init', 'remove_enfold_image_sizes');
function remove_enfold_image_sizes() {
// do NOT remove widget size, is used in backend portfolio items!
// remove_image_size('widget');
  remove_image_size('square');
  remove_image_size('featured');
  remove_image_size('featured_large');
  remove_image_size('portfolio');
  remove_image_size('portfolio_small');
  remove_image_size('gallery');
  remove_image_size('magazine');
  remove_image_size('masonry');
  remove_image_size('entry_without_sidebar');
  remove_image_size('entry_with_sidebar');
  remove_image_size('shop_thumbnail');
  remove_image_size('shop_catalog');
  remove_image_size('shop_single'); 
  remove_image_size('shop_gallery_thumbnail');
}