Keep state field as a dropdown when one allowed country on Woocommerce

I thought this would be easy but I'm not getting the results I want. Basically I have 2 countries in woocommerce CA and US. I'm trying to remove one conditionally, and I can do that with the following code below. However, when I go from 2 countries to 1, the dropdown menu still appears. An odd thing I'm noticing with the below code as well, is that if I go into my Woocommerce settings, then the country that is removed with this code is also removed from the "Sell to specific countries" options.... not sure what's going on. Thanks in advance.

add_filter( 'woocommerce_countries', 'custom_woocommerce_countries_limit');
function custom_woocommerce_countries_limit( $countries ) {     
        /*
        will place a conditional here if x then remove country
        */
        unset($countries['CA']);
        $countries = array(
            'US'  => __( 'United States', 'woocommerce' )
         ); 
    return $countries;
}

EDIT: Using this hook may be close to the answer, but when I use this one, The states don't turn into a dropdown...?

add_filter( 'woocommerce_countries_allowed_countries', 'custom_woocommerce_countries_limit');

You can use woocommerce_countries_allowed_countries filter hook, but you should need some additional code to force the state fields to be a state dropdown (select field):

add_filter( 'woocommerce_countries_allowed_countries', 'filter_allowed_countries_conditionally');
function filter_allowed_countries_conditionally( $countries ) {
    // will place a conditional here if x then remove country
    if( true ) {
        $countries = array( 'US'  => __( 'United States', 'woocommerce' ) );
    } else {
        $countries = array( 'CA'  => __( 'Canada', 'woocommerce' ) );
    }
    return $countries;
}

// Force billing state field type to be a dropdown
add_filter( 'woocommerce_billing_fields', 'filter_billing_state_fields', 100, 1 );
function filter_billing_state_fields( $fields ) {
    $fields['billing_state']['type'] = 'state';
    return $fields;
}

// Force shipping state field type to be a dropdown 
add_filter( 'woocommerce_shipping_fields', 'filter_shipping_state_fields', 100, 1 );
function filter_shipping_state_fields( $fields ) {
    $fields['shipping_state']['type'] = 'state';
    return $fields;
}

Code goes in function.php file of your active child theme (or active theme). Tested and works.