All three current derelicts are looted, but still active, if you need them. Check this thread for further updates, new wrecks will be spawned soon.
All very old derelicts, if necessary, might be melted without pinning in attack declaration thread to clean space and server.
EDIT: Some wrecks may look like 'players', so check playerlist too. You can read their infocards, if you use command /showinfo after player selection, or use appropriate button