themeszone

The plugin once activated will display a quantity field with increment / decrement buttons once add to cart button is pressed (e.g. the product is added to cart). 
Thus allowing customers to change the products number in the cart with out having to go to shopping cart 
page.
<a href="http://plugins.themes.zone" rel="nofollow ugc">PLUGIN DEMO</a> 
(click “Add to Cart button to see it in action”)
Feel free to ask any questions at <a href="https://themes.zone" rel="nofollow ugc">Themes Zone</a>

ThemesZone WooCommerce Ajax Quantity

ThemesZone WooCommerce Ajax Quantity Plugin shows quantity field on product listing once customer clicks "Add to Cart" button.

bhavik.kiri

This plugin will allow the customers to change the quantity using WooCommerce standard quantity field & delete the product on the WooCommerce checkout page.

Change Quantity on Checkout for WooCommerce

Works like a charm. Should be part of WooCommerce.

Does what it says on the tin!

Allow the customers to change the quantity & delete the product on the checkout page for WooCommerce.

ThemesZone WooCommerce Ajax Quantity vs Change Quantity on Checkout for WooCommerce