Just override the below code from functions.php of child theme
/*
CHANGE SLUGS OF CUSTOM POST TYPES
*/
if(!function_exists('service_slug')){
function service_slug( $args, $post_type ) {
/*service post type slug*/
if ( 'service' === $post_type ) {
$args['rewrite']['slug'] = 'our-services'; // Change our-service with your own slug
}
return $args;
}
//add_filter( 'register_post_type_args', 'service_slug', 10, 2 );
}