Yes. In NMC you can use filter under Media->Save Set and list what you want and delete those savesets after... or you can use mminfo to identify ssid list you want and delete those using nsrmm.

When you talk about "delete source files after backup", it is not backup, it's an archive operation. Nw has an option for that (but I don't think it will fit all your needs).

What you want to do is to have old files on a less costly media, but still have it available when you need. EMC DiskXtender is a product built for this purpose, there you can filter files and have them moved to tape or a slower disk, keeping pointers in the original filesystem to the moved file.

But if the only tool you have is Nw, you'll need to create a script to do that, I mean: list the files you want to move, send them to tape, check if the backup was finished fine and then remove them from the client. Worst part is to create the script that will list the files, because you may have to go down a huge folder structure. And keep in mind that the files on tape will expire some day, and then you won't have a copy of it in neither filesystem or tape.

I used a script once to do this a long time ago, but it was only one folder with a few redo log files that I need removed after the backup.

It sounds to me too like you want to do archiving and that DiskXtender is what you are looking for. It moves the data to a lower cost storage medium and leaves a pointer behind.
However I would proceed with caution about moving data to backup media and then deleting it - if you really have no need for it why have a backup in the first place? Do you have any more information as to why you would like to do this?

In process of listing files and folders, you would actually get into writing scripts on a daily basis and then be sure that backups were OK. I believe it would need a lots of manual intervention.

Ah silly me, right, this is archiving... for some reason I read it as he wants to delete source volume for cloning