The Workspace Settings >> People dialog lets you change the role people have within your workspace but be warned, it does come with some consequences.
Workspace roles are Admin, Member and Guest.
Admins manage billing, manage people within the workspace and can see usage.
Members can create and participate in rooms, create, manage and update packs.
Guests can only see published packs in rooms to which they are specifically invited.
Downgrading a person from Admin to Member will prevent that person from being able to manage the workspace however their roles within rooms are not changed. SO if they owned a room before the change then they will continue to own that room after the change.
Downgrading a person from Member to Guest will reduce their privileges in all rooms to Viewer, so they will no longer be able to participate as an Editor or Owner in those rooms.