I have implemented the ability to hide worlds from the /worlds list by default. As a result, i have hidden all old Recruits and Builder worlds, as well as works in progress.
You can see all worlds including hidden ones using /worlds all.
The reason for hiding these older maps, as well as works in progress (Notredame, for example), is to reduce the clutter of the /worlds list, while still retaining the maps within the server for others to see and work on.
Guest maps will be erased entirely as per usual though.