Deleting Exchange 2010 DB

Hi,

I'm unable to delete a an old DB after moving mailboxes to a new DB. I have checked that there are no mailboxes but when I check arbitration I get below.

Kindly advise am running Exchange 2010 SP2 on Server 2008 R2.

Name                      Alias                ServerName       ProhibitSendQuota
----                      -----                ----------       -----------------
SystemMailbox{1f05a927... SystemMailbox{1f0... MXSERVER          unlimited
SystemMailbox{e0dc1c29... SystemMailbox{e0d... MXSERVER          unlimited
FederatedEmail.4c1f4d8... FederatedEmail.4c... MXSERVER          1 MB (1,048,576 bytes)

Meshax