Two was to expire backups:
1. If previous backups were done to tape, you can list all media id's that contain valid backups and expire all images on each media id. Use the GUI reports and run Media List report or run bpmedialist from cmd.
Expire each media-id using bpexpdate command: bpexpdate -m <media-id> -d 0
2. If backups were done to disk, you need to list all image id's that falls within the period that you don't need anymore and expire them:
bpimagelist -idonly  -d <start-date>  -e <end-date>
bpexpdate  -backupid <backup id> -d 0

Some additional advice: Since you are new to NetBackup, read chapter 6 in Admin Guide I about NetBackup Catalogs.

i am using the disk backup.

After expiring the images. will the catalog be in consistent state

and

do i have to physically delete the backup files as well from the filer lun

thanx
hamza

problem solved

thanx very much Marianne van den berg.

u have been a great help

I want to request the forum moderator to increase her trusty rate

regards,
hamza