Clear cart data before adding new

How to clear cart data before adding new item to the cart ?

Solution:

1. Login to your wordpress backend.
2. Go to apperance > Theme Editor > functions.php
3. Add the following code/* Clear cart data before adding new */
   // before addto cart, only allow 1 item in a cart
   add_filter( ‘woocommerce_add_to_cart_validation’, ‘woo_custom_add_to_cart_before’ );function woo_custom_add_to_cart_before( $cart_item_data ) {global $woocommerce;
   $woocommerce->cart->empty_cart();// Do nothing with the data and return
   return true;
   } 
4. Save it . It works fine with all versions of WordPress and woo-commerce plugin.