Report size of Catalog DB per each Backup image

Go to "/usr/openv/netbackup/db/images" on your master server and check the folders which includes your clients hostname.
regards.

I'm wondering what you mean by "cleanup purpose ..."
Netbackup does its own cleanup of catalog files as they expire. I wouldn't mess with the catalog. It's the heart and soul of NetBackup.
It will do the cleanup at midnight and also some cleanup before it runs the catalog backup. This can also be done as frequently as you desire. Please see this technote for instructions:
The VERITAS NetBackup (tm) image database does not clean up expired images on the expiration date.
http://seer.support.veritas.com/docs/236274.htm