The old files are in the woocommerce folder of your theme. You don't need this folder per se and you can rename it (which is a more temporary way than deleting it flat-out) and WooCommerce will work. If you bought a theme, you could also contact their support and see about the purchase of an upgrade, because if the theme was up.
When you have important modifications in your templates, the super-fun task starts to equate old templates to current ones (which are in the WooCommerce design folder plugin).
The initial theme people had copied all the models of WooCommerce instead of only the ones they needed to change. In the end,