<?php

    function dequeue_previously_enqueued_script() {
        wp_dequeue_script( 'handle-of-previously-enqueued-script' );
        wp_deregister_script( 'handle-of-previously-enqueued-script' );
    }
    // Priority should be higher than priority of original enqueue
    add_action( 'wp_enqueue_scripts', 'dequeue_previously_enqueued_script', 100 );