/**
 * Put this code into your functions.php file
 * 3 = Strong (default)
 * 2 = Medium
 * 1 = Weak
 * 0 = Very Weak / Anything
 */
function raj_woocommerce_pass_strength( $strength ) {
    return 2;
}
add_filter( 'woocommerce_min_password_strength', 'raj_woocommerce_pass_strength' );