How to remove a Store form a Recovery Storage Group in Exchange 2003

[DJMC]

HI,
I am trying to remove a store from an exchange 2003 recovery storage group. When I dismount the store and click delete I get a message saying that there are users currently using the mailbox store and to move them to a different mailbox store before deleting.
How do I find which users are using this store, the logons folder is empty, I had previously deleted everything from the drive which holds the recovery data store?

Has anyone had problem removing a recovery storage group?

Any advice would be much appreciated.
D