Hide all levels except the current user's membership level from the list of membership levels on display

hide-membership-levels.php

<?php
/*
 * Hide some levels from Levels page
 */
function my_pmpro_levels_array($levels) {

    global $current_user;

    // if the user is logged in
    if (!empty($current_user->ID))
    {
        // remove all but the current user's level from the list of memberships
        foreach($levels as $key=>$level)
            if (isset($current_user->membership_level) && ($current_user->membership_level->id != $level->id))
                unset($levels[$key]);
    }

    return $levels;
}
add_filter('pmpro_levels_array', 'my_pmpro_levels_array');