Remove um-old-default.css

um-remove-css.php

<?php
/**
 * Remove um-old-default.css
 * UM Dequeue Old UM CSS File.
 * Removes the um-old-default.css
 */
add_action( 'wp_enqueue_scripts', 'remove_um_old_css', UM()->enqueue()->get_priority() + 1 );

if ( ! function_exists( 'remove_um_old_css' ) ) {
    function remove_um_old_css() {
       wp_dequeue_style( 'um_default_css' );
       wp_dequeue_style( 'um_old_css' );
    }
}