can i sell products not material? How to do it?

You can not disable the cart. Its a required part of woocommerce. But you can use third party plugins which adds direct checkout button on product or shop pages which redirects users directly to checkout page . One such plugin is

https://www.ads-software.com/plugins/woocommerce-direct-checkout/

regards

ok! thank you so much for your reply! can i use the booking calendar for the appointment in the woocommerce as well?

you will require third party addons for that as well . here are few such addons

https://www.ads-software.com/plugins/woocommerce-easy-booking-system/
https://www.woothemes.com/products/woocommerce-bookings/
https://codecanyon.net/item/booking-system-pro-wordpress-plugin/2675936

make sure the what you are looking for is available with any product before making purchase.

regards

Thanks you so much again!