You can change the name and specification of an existing room type (room class, description, prefix and number of guests), however, please note that:
1) the room type name will also change in all the bookings related to it (past and future)
2) the room type name will also change in all the rooms connected to it
For example, I want to change my Twin Room Shared Bathroom to Deluxe Double Room Ensuite with Balcony. I have two physical rooms on Bed View with this room type.
I can edit the current Twin Room Shared Bathroom in Room Manager:
So I change the Room Class to Double, Bathroom to Ensuite, add a Prefix (Deluxe) and a Description (with Balcony):
After this change I have the new room type, Deluxe Double Room Ensuite with Balcony, on Bed View and in already existing reservations which had the previous room type assigned: