/ssm max_number
To set a max of soul shards (saved per character), 0 is infinite
/ssm
To delete if you have too much shards. Just macro it into Life Tap or Drain Soul or by itself.
It cannot be fully automatic after combat because the related wow api needs a hardware event.
It delete in priority outside your soul bag, from right to left inside your bags, and takes into account the GetInsertItemsLeftToRight variable to delete from the bag supposed to be filled first.