Once a host has defined their session's category and type of session during the new listing process, a host isn't able to change a listing's category or type afterwards. However, a host is able to modify all other details such as descriptions, pricing and more.
The reason for this is so that existing clients or people are not thrown off by the session details completely changing on them (imagine a personal training session turning into a cooking lesson...that would just be really confusing on people).
If a host needs to update the listing's category or type, you would have to create a brand new listing.
If you have any questions, ideas on how we make your experience better, or simply just to connect with us, contact us at firstname.lastname@example.org. We're happy to listen and help!