Can't delete a Disk Pool

Understand this sequence will help you in future to determine why and how:

When you first create a disk storage unit (using AdvancedDisk, PureDisk, DataDomain etc.), you will need to:

1) Create a storage server
2) Create a disk pool
3) Create a disk volume (which maybe automatically taken care of by Netbackup)
4) Create a disk storage unit
5) Start backup (writing images into disk)

So when you go the other way round, to delete a disk pool, you will need to first:

5) Remove images from the disk
4) Delete the disk storage unit
3) Delete the disk volume

...before you can delete the disk pool. 

Another important note is, before deleting disk volume and disk pool, you need to make sure you set their state to DOWN. That can be done using nbdevconfig -changestate command, you can look for more details of that command using the Netbackup CLI admin guide.

You need to expire all disk images before deleting disk pool.

See http://www.symantec.com/docs/TECH181842

What kind of Disk pool is this.

Check for Associated Disk Unit

Expire All images from Disk Unit

Delete Disk Unit

Then Delete Disk Pool

Then you can Delete Storage Server (If required)

based on Solution on newer thread it looks like

 nbdelete -allvolumes

did the trick?

yes.

It is just fair to give acknowledgement and credit where it is due...

We normally award the post that as helped the most as Solution.

I have taken the liberty of doing so on your behalf.............

thank you.