Exclude Post ID from Array Specified in Custom Field

Your question is pretty vague and you haven’t given any example code, but the following may work for you:

<?php

    global $post;

    // Arguments
    $args = array('
        /* Enter your arguments in here... */
    ');

    // The query
    $the_query = new WP_Query( $args );

    // The loop
    if ( $the_query->have_posts() ) {

        // Exclude ID
        $exclude_id = get_post_meta( $post->ID, 'exclude_field', true );

        while ( $the_query->have_posts() && $post->ID !== $exclude_id ) {
            $the_query->the_post();

            /*
                Output here, e.g.
                echo '<h2>' . get_the_title() . '</h2>';
                echo '<div>' . get_the_content() . '</div>';
            */

        }
    }

?>