On woocommerce how do I remove this cropping to product catergory thumbnails?

Update for WooCommerce 3.4

The thumbnail sizes are now available in the Customizer. You'll need to open the Customizer, then select WooCommerce, then Product Images.

The "main image" is the single product image. And the "thumbnail" is the shop/archive loop image.

The settings are no longer available in the admin Settings.

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The category images are the same size as shop_image (or Catalog) thumbnail. WooCommerce handles its product thumbnails in its settings:

WooCommerce->Settings>Products>Display

You can change its height, width, and toggle the hard crop on/off.

After changing the image sizes you will need to regenerate thumbnails.