How can I “bulk remove” Rooms from Games lessons?

Removing Rooms from Lessons "en masse"

  Q.   Is there any way of “bulk removing” Rooms from Games lessons?
On my timetable at the moment all the Academic staff scheduled for Games teaching are apparently coaching hockey/rugby etc., in their “own” classrooms, which could make rather a mess.  (And more importantly I need those rooms to house peripatetic teachers.)

  A.  Go to "Rooming Overview -> Global room change" and select "Games" as the subject (leaving all other fields saying "any teacher" etc)
... and either make sure that "New room" is "none/remove", or enter the "New Room" as "Field" or "Gym".
[Make sure that "Field" or "Gym" are already on your Rooms List on the Rooms Screen].