Problem with deregistering boot server

I want to deregister the boot server of AIX 5.3.11.1 with netbackup 7.0. My master server in Windows 2008.

While I issuing the command "./bmrsetupboot -deregister"  on AIX boot server it shows the following error

[Error] V-127-72 A boot server that is currently hosting Shared Resource Trees cannot be deleted.
Please delete all the Shared Resource Trees hosted by the boot server, and retry the operation.

Could ant one give me the solution?