Remove WordPress images sizes - all except thumbnail
<?php
add_action( 'after_switch_theme', 'theme_activated' );
add_filter( 'intermediate_image_sizes_advanced', 'remove_default_sizes');
function theme_activated() {
// Set thumbnail size in settings > media.
update_option( 'thumbnail_size_w', 150 );
update_option( 'thumbnail_size_h', 150 );
update_option( 'thumbnail_crop', 1 );
// Set medium size in settings > media.
update_option( 'medium_size_w', 0 );
update_option( 'medium_size_h', 0 );
// Set large size in settings > media.
update_option( 'large_size_w', 0 );
update_option( 'large_size_h', 0 );
}
function remove_default_sizes( $sizes) {
unset( $sizes['medium']);
unset( $sizes['large']);
unset( $sizes['medium_large']);
return $sizes;
}