In the vsphere web client you can go to the restore tab and select multiple backups to delete within each client. So if you have multiple points in time for one client to delete its quick. If you want to delete multiple clients backups I'm not aware of a quick way.
You could script the delete using mccli but it would require some knowledge about how it works that is not documented by vmware and would not be for the faint of heart. I highly doubt mccli is fully supported by vmware so use at your own risk. Even if it was supported it would probably still be quicker to delete each backup in the the VDP webclient. Thinking way outside the box one possible work around would be to create a new VDP appliance and replicate the backups you want to save to it then delete the old appliance. Although you would probably have to recreate all your backup jobs on the new appliance so I doubt its what your looking for.