Changing existing custom post type name without plugin

Hello fellow WordPress users,

I have an assignment to make a webshop using the 456market theme and WooCommerce.

The 456market allready installed Portfolio as a custom post type. I want to use this post type because it is used in the theme. I just want to change the name because we are not going to use this function as a portfolio.

Could you tell me how I can change the name Portfolio in another name without using a plugin and without changing the theme?

I allready have a child theme running for minor changes, so the updates won’t mess up everything.