Woocommerce - Disable all payment methods but free shipping and local pickup when free shipping is available

disable-payment-methods-when-free-shipping-available.php

<?php
function my_hide_shipping_when_free_is_available( $rates ) {
    $free = array();     
    foreach ( $rates as $rate_id => $rate ) {                                             
        if ( 'free_shipping' === $rate->method_id ) {                        
            $free[ $rate_id ] = $rate;                    
            break;
        }
    }
    foreach ( $rates as $rate_id => $rate ) {
        if ( ( $free ) and ( 'local_pickup' === $rate->method_id ) ) {
            $free[ $rate_id ] = $rate;
            break;
        }
    }
    return ! empty( $free ) ? $free : $rates;
}
add_filter( 'woocommerce_package_rates', 'my_hide_shipping_when_free_is_available', 100 );