The volume copy was not deleted because an image mode copy might contain inconsistent data.
Make sure that you specified the correct volume. If so, wait for the restore operation to complete, or cancel the restore. Use the management GUI or the lsvolumerestoreprogress command to monitor the progress of the restore operation, or the restorevolume command to cancel the restore operation. Alternatively, specify the -discardimage parameter to force-delete the volume copy.