When editing a lodging type, you can manage the room inventory for the lodging type.
At the bottom of the page, there is a section labeled Room inventory.
This section has a searchable dropdown that can be used to add and remove rooms from the lodgings room inventory.
Simple click the dropdown icon, and it will show the list of rooms, and the lodging types those rooms currently have.
Click into the whitespace of the dropdown, and start typing, and it will search and filter the dropdown list.
Click the rooms in the dropdown list to add them to the dropdown select box.
Xicon on the room item button to remove the room from the dropdown select box. You can also remove rooms clicking into the search area, and pressing down the backspace button on your keyboard.
Click the Update button to save the changes to the room inventory.
You can also click the label of the room button to open a new tab to edit that room.
Here is a screen recording of how to do those steps.