woocommerce-disable-paypal-for-subscriptions.php

<?php
/**
 * Plugin Name: WooCommerce Disable PayPal for Subscriptions
 * Plugin URI: https://gist.github.com/thenbrent/6641526
 * Description: Want to disable PayPal for subscription purchases, but still offer it as an option for buying one-off products? Activate this plugin.
 * Author: Brent Shepherd
 * Author URI: http://find.brentshepherd.com/
 * Version: 1.0
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @author    	Brent Shepherd
 * @since		1.0
 */

function wcsdp_get_available_payment_gateways( $available_gateways ) {

	if ( class_exists( 'WC_Subscriptions_Cart' ) && ( WC_Subscriptions_Cart::cart_contains_subscription() || ( isset( $_GET['order_id'] ) && WC_Subscriptions_Order::order_contains_subscription( $_GET['order_id'] ) ) ) ) {
		if ( isset( $available_gateways['paypal'] ) ) {
			unset( $available_gateways['paypal'] );
		}
	}

	return $available_gateways;
}
add_filter( 'woocommerce_available_payment_gateways', 'wcsdp_get_available_payment_gateways', 11 );