The ER really creates one DB on each instance of online. The DB names : syscdr.
This DB is created when you write: cdr define server <servername>.
To remove the ER you must do: cdr delete server <servername> on each instance. This drops the syscdr database and then you can again define the ER using the cdr define server command.
If with cdr delete serv command you canīt remove the syscdr database you can do drop it manually.